Answer:
The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Five elements are less frequently so classified: carbon, aluminium, selenium, polonium, and astatine.
Explanation:
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Question 9(Multiple Choice Worth 5 points)
(01.02 LC)
Which of the following is true about the weight of an object?
O It remains same for the object.
O It cannot be measured accurately.
O It is a force acting on the object.
O It is always less than the mass of the object.
PLS HELP
Answer:
It is a force acting on the object.
Explanation:
The answer option which is true about the weight of an object is: C. It is a force acting on the object.
Weight can be defined as the force acting on a physical body or an object as a result of gravity. Also, the weight of an object is measured in Newton.
Mathematically, the weight of an object is given by the formula;
Where;
m is the mass of the object.
g is the acceleration due to gravity.
In conclusion, the weight of an object is the force acting on an object due to gravity.
how does the shape of a molecule affect its smell?
Answer:
it affects the speed of movement.Because the bigger the molecules the more time they will take to diffuse or smellIn a titration of 12.5 ML of 0.20m NaOH is used to neutralize 10.0 ML of HCL. Calculate the acid concentration
=> 0.25 M
The question is asking us to find the molarity/concentration of the acid (HCl).
We have been provided with;
12.50 mL of 0.20 M NaOH
10.0 mL of HCl
We know that molarity (M) of a solution is contained in 1 L or 1000 mL or 1000 cm³.
This means that;
0.20 M is contained in 1000 mL.
X mol is contained in 12.50 mL
[tex] x \: mol \: = \frac{12.50 \times 0.20}{1000} \\ = 0.0025 \: moles[/tex]
= 0.0025 moles
These 0.0025 moles is contained in 10 mL of HCl.
To find the molarity of the acid;
0.0025 moles is contained in 10 mL
x mol is contained in 1000 mL
[tex]x \: mol \: = \frac{0.0025 \times 1000}{10} \\ = 0.25 \: mol[/tex]
= 0.25 M
Therefore the Concentration of the acid (HCl) is 0.25 M
Mia has a 32.0 g sample of Fe(OH)3 for the investigation purpose. How many
grams of oxygen be recovered from the sample?
O 3.6g
21.6 g
7.2 g
O 14.4 g
The amount of oxygen that can be recovered would be 14.37 grams
Percentage composition[tex]Fe(OH)_3[/tex] has 3 atoms of oxygen.
The percentage oxygen composition in the compound can be calculated as:
mass of oxygen content/total mass
The molar mass of the compound is 106.87 g/mol.
Percent oxygen = 3 x 16/106.87 x 100% = 44.91%
Thus, the amount of oxygen that can be recovered from 32.0 grams of Fe(OH)3 will be:
44.91/100 x 32 = 14.37 grams
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Gina predicts that one really large cube of sugar will dissolve faster than the same
amount of sugar in several medium-sized cubes. She thinks that because there is only
one larger cube, it has more surface area and will dissolve faster than the several
medium-sized cubes. What is the best assessment of Gina's prediction?
The best assessment of Gina's prediction is that the several medium-sized cubes will dissolve faster than the large cube of sugar.
How does surface area affect solubility?The surface area of a substance refers to the total area on the surface of that object.
Surface area plays a vital role in the dissolution of a substance. When a solute dissolves, the action takes place only at the surface of each particle.
This suggests that when the total surface area of the solute particles is increased, the solute dissolves more rapidly, hence, the best assessment of Gina's prediction is that the several medium-sized cubes will dissolve faster.
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How many moles of sodium atoms is 5.43 x 10^24 atoms of sodium? *
Answer:
9.02 moles Na
Explanation:
To find the amount of moles, you need to multiply the given amount by Avogadro's Number. This number allows you to convert from atoms to moles of any substance.
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
5.43 x 10²⁴ atoms Na 1 mole
-------------------------------- x --------------------------------- = 9.02 moles Na
6.022 x 10²³ atoms
Using the equation
C12H22O11+12O2-->12CO2+11H2O
if 156 L of O2 at STP are consumed how many moles of sucrose are required?
Answer:
0.5804 moles sucrose are required to react with 156 liters of oxygen.
Explanation:
Since the conditions of the gas are STP, standard temperature and pressure, we can use a very useful conversion factor that is valid for all gases at STP: All gases occupy 22.4 liters per mole of gas:
22.4 L/mole
156 liters of O2 at STP may be converted to moles O2 by dividing by the conversion factor:
(156 L)/(22.4 L/mole) = 6.96 moles O2
The balanced equation tells us that 12 moles of O2 are consumed for every 1 mole of sucrose. That's a molar ratio of (1 mole sucrose/12 moles O2).
We can use this ratio to determine the moles of sucrose required to react with 6.96 moles of O2:
(6.96 moles O2)*((1 mole sucrose/12 moles O2) = 0.5804 moles sucrose
In general, when the addition of an unsymmetrical electrophilic reagent to an unsymmetrical alkene forms the product predicted by Markovnikov's rule, that occurs because: A) the product is statistically favored. B) steric hindrance favors its formation. C) it is formed via the more/most stable carbocation. D) it is the more/most stable product. E) All of these choices are reasons.
It is formed via the more/most stable carbocation.
What justification exists for Markovnikov's Rule?
A carbocation is created as a result of the protonation of the alkene by the protic acid. The carbocation that has the most alkyl substituents on its carbon holds the positive charge, making it the most stable carbocation. As a result, the addition of the halide to the carbon that has fewer hydrogen substituents makes up the majority of the product.
Markovnikov's rule
According to the Markovnikov rule, a proton is added to the carbon atom with the greatest number of hydrogen atoms connected in addition to processes involving alkenes or alkynes.
Anti-Markovnikov Rule
According to the Anti-Markovnikov Rule, in addition to reactions between alkenes or alkynes, The carbon atom with the fewest hydrogen atoms linked to it receives the proton.
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Write the empirical formula of a list for binary ionic compounds that could be formed from the following ions
Answer:
CaBr₂, CaO, FeBr₂, FeO
Explanation:
Per binary compound, there must be 1 cation (Ca²⁺, Fe²⁺) and 1 anion (Br⁻, O²⁻). The compound should have a charge of 0 (neutral). For this to occur, there sometimes needs to be more than one cation/anion present in the compound. Below I have included the math that displays why there are more ions necessary in some compounds.
CaBr₂
-----> Ca = +2 and Br = -1
-----> +2 + (-1) + (-1) = 0
CaO
-----> Ca = +2 and O = -2
-----> +2 + (-2) = 0
FeBr₂
-----> Fe = +2 and Br = -1
-----> +2 + (-1) + (-1) = 0
FeO
-----> Fe = +2 and O = -2
-----> +2 + (-2) = 0
An aqueous solution contains
32.7% KCI (weight/weight %).
What is the mole fraction of KCI in
this aqueous solution?
Molar Mass
KCI: 74.55 g/mol
H₂O: 18.016 g/mol
Enter text here
Enter
Answer:
0.105 KCl
Explanation:
(Step 1)
If the solution is 32.7% KCl, we can assume that there are 32.7 grams KCl in the solution. This means that there would be 67.3 grams H₂O (100% - 32.7% = 67.3%) in the solution.
32.7% KCl = 32.7 g KCl
67.3% H₂O = 67.3 g H₂O
(Step 2)
Now, we need to convert both the solute (KCl) and the solvent (H₂O) into moles. This can be done by multiply the grams of each substance by their molar masses.
32.7 g KCl 1 mole
------------------ x -------------------- = 0.439 mole KCl
74.55 g
67.3 g H₂O 1 mole
------------------ x ----------------- = 3.74 moles H₂O
18.016 g
(Step 3)
Finally, we can calculate the mole fraction of KCl using the following equation. The final answer should have 3 sig figs to match the given value with the lowest amount of sig figs (32.7 g).
moles of solute
Mole Fraction = -----------------------------------------------------
moles of solute + moles of solvent
0.439 mole KCl
Mole Fraction = ------------------------------------------------------
0.439 mole KCl + 3.74 moles H₂O
Mole Fraction = 0.105 KCl
Which statement best describes the science of chemistry?
A. Chemistry is mainly the study of energy and forces in matter in the
universe.
B. Chemistry is mainly the study of forces in matter.
C. Chemistry is mainly the study of the composition of and changes
in matter.
D. Chemistry is mainly the study of matter in living things.
Answer:
Explanation:Matter is anything that has weight and occupies space
what might be a scientific question
Answer:
Example of a scientific question:
Does the angle of a ramp change the distance a toy car will travel?
Explanation:
The oxidation number of an element in a compound is equal to the charge the atoms would have if the compound was ___________. Select the correct answer below: ionic covalent molecular
The oxidation number of an element in a compound is equal to the charge of the atoms if the compound was an ionic compound.
What are types of compounds and how their oxidation number is calculated?The types of compounds are:
Ionic compoundsCovalent compounds and Molecular compoundsIonic compounds:
When a metal reacts with a non-metal an ionic compound is formed.The metal and ono-metals share electrons in between them and forms an anion and a cation respectively.The oxidation number of an ionic compound is equal to the charge of the ion.For a polyatomic ion, the sum of the oxidation numbers is equal to the charge of the ion.Covalent compound:
When non-metals reacts together a covalent compound is formed.They share electrons in between them by forming a covalent bond.The oxidation number of a covalent compound is the charge that results when the electrons are assigned to the more electronegative atom.Molecular compounds:
Molecular compounds are like the covalent compounds shares a covalent bond in between the atoms.The oxidation number of a molecule is given by gaining or losing of an electron by the atoms in it.Therefore, the oxidation number of an element in a compound is equal to the charge of the ion that would have if the compound was an ionic compound.
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A nonpolar solvent has the highest solubility with a(n) _____ solute. A. polar B. nonpolar C. ionic D. electrically charged solute.
Answer:
nonpolar
Explanation:
A nonpolar solvent has the highest solubility with a nonpolar solute.
What is the symbol for temperature?
m
q
T
J
Answer:
T
Explanation:
m is mass
q is heat
J is energy
what is the bond formed between N and Br
A) non-polar covalent
B) Polar Covalent
C) Ionic
Answer:
Bond between N and Br is non polar bond
Nitrogen being the element of group 15 , it required only 3 electrons to complete it's octace and BR, element of group 17 requires only one electron to complete it's octace both nitrogen and br share their electrons as for forming ionic bond it requires too much energy for nitrogen to remove 3 electrons also here, valency of br is only one. both are non metal so they formed covalent bond.Which is the correct name for p2o5? phosphorus dioxide phosphorus pentoxide diphosphorus pentoxide diphosphorus hexaoxide
Correct option:
The correct name for [tex]P_{2}O_{5}[/tex] is diphosphorus pentoxide.
Why [tex]P_{2}O_{5}[/tex] is called diphosphorus pentoxide?
[tex]P_{2}O_{5}[/tex] is commonly known as diphosphorus pentoxide.
Phosphorus pentoxide has an intriguing property in that [tex]P_{2}O_{5}[/tex] is actually its empirical formula, whereas [tex]P_{4}O_{10}[/tex] is its actual molecular formula.
However, the name of the chemical was obtained from its empirical formula rather than from its molecular formula. The official name for this substance is diphosphorus pentoxide.
Oxygen-containing binary compounds have "oxide" as their "last name." Phosphorus is the "first name."
We list each atom's numbers below:
The di- and Penta- prefixes are used to indicate the presence of two and five oxygen atoms, respectively, in the molecule.
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Answer:
diphosphorus pentoxide
Explanation:
what made alchemy unscientific in its practice?
Answer:
Because it was not based on evidence and experiment.
Why isn't alchemy considered a science?
Alchemy isn’t rigorous enough.
People began to realize that it was possible to transform one material into another in antiquity. The study of how to achieve this was known as alchemy. Alchemists would experiment on various substances, trying to turn lead into gold or to create the elixir of life.
They were unaware of what was taking place in the background, though. They weren't as rigorous as contemporary science. seldom ever exchanged their discoveries. And technically speaking, they carried out their experiments before the formalization of the scientific process.
In a way that made perfect sense to the alchemists but makes no sense at all to us, alchemy blurs the lines between empirical observation and experimentation, irrational conjecture, and mysticism. The last two render it unscientific.
Alchemy became known as chemistry once the scientific approach was established and mysticism was eliminated. Because alchemy particularly refers to the earlier, less scientific kind of chemistry, we no longer view it as a science.
Calculate the amount of sucrose required to prepare 250g of 5%
solution of glucose by mass? Also determine the mass of solvent
used to prepare this solution.
The amount of sucrose required will be 12.5 grams and the mass of water required will be 250 g.
Stoichiometric problem5% by mass glucose solution is to be prepared. This means that 5g of glucose will be dissolved in 100 mL of water.
250g of such a solution will require 250 mL of water.
5% of 250g = 5/100 x 250 = 12.5 grams
Thus, the solution is prepared by dissolving 12.5 grams of sucrose in 250 grams (250 mL) of water.
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The value of Gfor a reaction conducted at 25C is 2.8 KJ/mol. The equilibrium for a reaction is _____ at this temperature.
The equilibrium constant of the reaction is 0.323.
Equilibrium constant:
It is expressed as the ratio of concentration of the products to the concentration of reactants. It is represented by K.
The relationship of K with G (Gibbs free energy) is expressed as:
G° = -RTlnK
Here R is the gas constant, T is the temperature.
Calculations:
Convert 25°C to K.
25°C = (25 + 273.15) K
= 298.15 K
Substitute the values in the above expression.
2.8 x 1000 J/mol = -8.314 J/mol.K x 298.15 K x ln(K)
lnK = 2800 J/mol/(-8.314 J/mol.K x 298.15 K)
lnK = -1.13
K = e^-1.13
= 0.323
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Compare the atomic sizes of sodium and magnesium. Explain.
Answer:
Sodium atom is larger than Magnesium atom.
Explanation:
Looking at the electronic configurations of Sodium and Magnesium:
[tex]_{11}Na: 1s^2 2s^2 p^6 3s^1\\\\_{12}Mg : 1s^2 2s^2 p^6 3s^2[/tex] ,
we can see that they both have their valence electrons in the 3rd shell.
But because Magnesium has a higher nuclear charge of +12 because of its 12 protons than that of Sodium's +11, the nucleus of Magnesium attracts its outer electrons more strongly than Sodium does. This makes the Magnesium atom smaller.
In molecules, c, h, o, and n atoms usually make __, __, __, and __ bonds respectively
Answer: " 4, 1, 2, 3."
_______________
" In molecules, C, H, O, and N atoms usually make _4_, _1_, _2_, and
_3_ bonds, respectively."
_______________
Note the following mnemonic device:
" H O N C " —> "Honc" if you love molecules!"
1 2 3 4 ;
{"hydrogen"} H → 1
{"oxygen"} O → 2
{"nitrogen"} N → 3
{"carbon"} C → 4
___
So: by using this mnemonic:
H O N C ;
1 2 3 4 ;
___
→ We can answer the question:
" C, H, O, N " → in sequence:
" 4, 1, 2, 3 " ;
{just use the corresponding numbers as per the mnemonic device.}.
The answer: " 4, 1, 2, 3 ".
Hope this is helpful to you! Best wishes!
How many grams of NH3 form when 22g H2 react completely?
The Answer to the question is 124.66 grams approximately.
It is given that H₂ will react completely
Molar mass of H₂ = 2 × 1 = 2 gm/mol
Given mass of H₂ = 22 gm
Moles of H₂ reacting = given mass of H₂ / molar mass of H₂
Moles of H₂ reacting = 22 / 2 moles = 11 moles
So, 11 moles of H₂ are taking part in reaction.
The Balanced chemical reaction is as follows as:
N₂ + 3 H₂ → 2 NH₃
It is clear from the reaction that 3 moles of H₂ are making 2 mole of NH₃
3 moles of H₂ → 2 mole of NH₃
1 moles of H₂ → 2/3 mole of NH₃
11 moles of H₂ → (2/3)×11 mole of NH₃
11 moles of H₂ → 22/3 mole of NH₃
So, 11 moles of H₂ will make 22/3 mole of NH₃
22/3 mole NH₃ = mass formed NH₃ / molar mass of NH₃
mass formed NH₃ = 22/3 × molar mass of NH₃
mass formed NH₃ = 22/3 × 17
mass formed NH₃ = 22/3 × 17
mass formed NH₃ = 124.66 grams (approximately)
124.66 grams of NH₃ will be formed.
So, approximately 124.66 grams of NH₃ is formed from 22 grams of H₂.
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Which type of molecule carries genetic information?
OA. Triglyceride
OB. Polypeptide
OC. Nucleic acid
OD. Polysaccharide
Answer:
Nucleic acid
Explanation:
Because nucleic acid is the molecule that carries genetic information because it helps to develop or functioning an organism
A sample of metal has a mass of 16.5916.59 g, and a volume of 5.815.81 mL. What is the density of this metal
Answer:
=> 2.8554 g/mL
Explanation:
To determine the formula to use in solving such a problem, you have to consider what you have been given.
We have;
mass (m) = 16.59 g
Volume (v) = 5.81 mL
From our question, we are to determine the density (rho) of the rock.
The formula:
[tex]p = \frac{m}{v}[/tex]
Substitute the values into the formula:
[tex]p = \frac{16.59 g}{5.81 mL} \\ = 2.8554 g/mL[/tex]
= 2.8554 g/mL
Therefore, the density (rho) of the rock is 2.8554 g/mL.
If 82.5 mol of an ideal gas occupies 10.5 l at 317 k, what is the pressure of the gas?
P=20707.7 atm
What is the molar form of the ideal gas law?The ideal gas law is a straightforward formula that describes the relationship between an ideal gas's pressure P, volume V, and temperature T. Unless there is a strong reason to treat gases differently, we normally treat gases as ideal because of how straightforward this relationship is:-
PV=nRT
where ;
P= Pressure=?
V= Volume= 10.5 L
n= no.of mol.= 82.5 mol
R=Ideal gas constant= 8.314 joule / mol kelvin
T=Temperature= 317 K
using Given value:-
P= nRT/ V
P=(82.5 x 8.314 x 317) / 10.5
P=20707.7 atm
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If a radioactive decay produced 1.26 × 1012 J of energy, how much mass was lost in the reaction?
The mass lost in the process is 1.4 * 10^-5Kg.
What is the Einstein equation?The Einstein equation is able to relate the mass lost to the energy that is evolved in a nuclear process.
Given that;
E = Δmc^2
Δm = E/c^2
Δm = 1.26 × 10^12 J/( 3 * 10^8)^2
Δm = 1.4 * 10^-5Kg
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In balancing an equation, we change the __________ to make the number of atoms on each side of the equation balance.
Q1. What are decomposition reactions? Explain with the help of a balanced chemical equation. (2 marks)
Q2. Draw the structure of a nephron and label the following on it- Glomerulus, Bowman’s capsule, Renal artery and Collecting duct. (2 marks)
Q3. What happens when zinc metal reacts with sulphuric acid? Write the chemical equation involved in this reaction. (2 marks)
Q4. Draw ray diagrams showing the image formation by a convex lens when an object is placed (2 marks)
(a) between optical centre and focus of the lens
(b) between focus and twice the focal length of the lens
Q5. Sunita and her mother had an appointment with an optician. Optician prescribed corrective lenses to Sunita having a power equal to + 5.0 D. The lens prescribed to
her mother has power equal to – 2.5 D. (3 marks)
(a) What is the focal length of the lens prescribed to Sunita?
(b) Which type of spherical lens is prescribed to Sunita’s mother?
(c) What is the power of the combination of the two lenses (if placed in contact), prescribed to Sunita and her mother?
Q6. Give the reason for the following: (3 marks)
(a) The taste and smell of chips change when the packet is left open for a few days.
(b) Magnesium ribbon is cleaned before burning in air.
(c) Iron articles get coated with reddish brown powder when left for sometime.
Q7. (a) Why do arteries have thick and elastic walls while veins have thin walls? (2 marks)
(b) What is the role of valves in the heart? (1 mark)
Decomposition reaction represents the breakdown of single compound into more products.
What are decomposition reactions?A decomposition reaction is a type of reaction in which one reactant breaks down into two or more products. This can be represented by the general equation: H2O2 → 2H + 2O. In this example the breakdown of hydrogen peroxide occurs and water and oxygen are formed.
What happens when zinc metal reacts with sulphuric acid?Zinc reacts with dilute sulphuric acid to form zinc sulphate and hydrogen This hydrogen goes up into the atmosphere whereas the zinc sulphate remains.
Why should a magnesium ribbon be cleaned before burning in air?Magnesium ribbon should be cleaned before burning in air because Magnesium metal combines with oxygen to form Magnesium Oxide (MgO) layer, which is a very stable molecule.
Why arteries have thick, elastic walls, while veins have thin walls?Arteries have thick, elastic walls, while veins have thin walls because arteries are under more pressure, as compared to veins that are under less pressure. Arteries are big in size whereas veins are small.
What is the role of valves in the heart?The role of valves in the heart is that these valves prevent the backward flow of blood.
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What is the correct ratio of the atoms of the two elements present in a sample of the compound copper chloride, CuCl2?
Each answer will be formatted as Copper : Chlorine .
Select one:
a. 0:0
b. 2:1
c. 1:2
d. 1:1
The correct ratio of the atoms of the two elements in the sample of copper chloride compound would be 1:2.
Atoms of elementsCopper chloride has a chemical formula, [tex]CuCl_2[/tex].
Thus, an atom of copper, Cu, combines with 2 atoms of chlorine, Cl.
The 2 chlorine atoms are recipients of an electron each from the copper atom which happens to have 2 electrons in its outermost valence shell.
Therefore, the ratio of copper to chlorine atoms in the compound is 1:2.
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