what is the formula for H-H

Answer:

endothermic reaction

Explanation:

When Elsa from Frozen freezes things, it is an example of an endothermic chemical reaction.

An endothermic involves a reaction in which heat is absorbed from the surrounding. Hence the surrounding becomes colder at the end of the the change.

So, Elsa draws heat from the environment and this causes the environment to be colder and things that are in contact with her.

Answer:

Answer:

Reversible

Explanation:

Changes of state are physical changes in matter. Common changes of the state include melting, freezing, sublimation, deposition, condensation, and vaporization.

Answer:

0.864 g/mL.

Explanation:

I hope this helps u! also have a great rest of your day!

Answer:

Distance between C-C in ethane- 1.54 Å

Distance between H atoms in eclipsed conformation-2.3 Å

Distance between H atoms in staggered conformation- 2.5 Å

Staggered conformation is more stable

Explanation:

The staggered conformation of ethane can be demonstrated as the most stable of conformation of ethane, because the angles between Carbon-Hydrogen bonds in both the front and back carbon atoms are maximized.  This now minimizes the energy of this conformation compared to the eclipsed conformation.

Considering the eclipsed conformation, it is obvious that the electron densities on Carbon-Hydrogen bonds come very close together thereby bringing two C-H bonds  into a dihedral angle of almost zero degrees. This causes their electron clouds to experience strong repulsion, thereby raising the molecules's total energy.

Answer:

The proportions in which the respective gases from each cylinder should be used; C1 : C2 : C3 = 1 : 2.308 : C3

Explanation:

Given that;

CH4 to C2H6 =  1.3 to 1

Cylinder 1 =  70% N2 and 30% CH3

Cylinder 2 = 90% N2 and 10% C2H6

Cylinder 3 = ( pure N2 ) = 100% N2

CH4 to C2H6 =  (1.3 to 1)

we have CH4 and C2H6 in cylinder 1 and 2 only

we only have balance material in c1 and c2

Now, Let x be from cylinder and ( 1-x ) be from cylinder 2

so, 30x / 10( 1-x ) = 1.3 / 1

30x = (10 - 10x)1.3

30x = 13 - 13x

30x + 13x = 13

x = 13/43

x = 0.3023

Also, ( 1-x ) = ( 1 - 0.3023) = 0.6977

so

C1/C2 = 0.3023/0.6977 = 1 / 2.308   while c3 can be anything;

Therefore, C1 : C2 : C3 = 1 : 2.308 : C3

Answer:

Explanation:

The aim of this question is to draw the structure of genistein and determine the number of atoms with sp² hybridization in the molecule.

From the image below, we will see the lewis structure of genistein. From the image, the blue asterisk atoms are sp² hybridized and the red marked atoms are sp³ hybridized.

We will also notice that all the carbon atoms contain 3 σ-bonds with no lone pair of electrons.

Using the knowledge of Valence shell electron repulsion theory (VSEPR), the above-mentioned carbon atom is said to be sp²hybridized.

Also, the oxygen atoms which are doubly bounded contains 1 σ-bond and 2 lone pair electrons. These oxygen atoms are also sp² hybridized.

Finally, the singly bonded oxygen atom is composed of 2 σ-bonds and 2 lone pair electrons. This makes it to be sp³ hybridized.

Altogether, we have a total of 16 sp² hybridized atoms and 4 sp³ hybridized atoms.

Answer:

Weather is at a specific place and time. Climate is over a period of time.

Explanation:

That is the difference

Answer:

Large crystals

Slowly

Explanation:

Recrystallization is a procedure used to purify an impure compound in a solvent. The concept used here is that the solubility of most of the solids increases with increase in temperature.

Recrystallization is also called as method of fractional crystallization.

After a recrystallization, a pure substance will ideally appear as a network of large crystals. If this is not the case, it may be worthwhile to reheat the flask and allow the contents to cool more slowly.

Answer:

C) tellurium (Te) is the correct answer.

Answer:2NaF + Br2 —> 2NaBr + F2

2K + Cl2 —> 2KCl

N2+ 3F2 —> 2NF3

Explanation:

Answer:

look it updjk jkj vjx cv xckv

Explanation:

look it upvjcvjkcxjbvjkcvbjbcxkjvjdbfcvbdw uvd vjbvjfjv jdbv

Answer:

element :

a substance that is made up of only one type of atom

I hope it helps you ✌

Answer:

1.51×10²³ atoms.

Explanation:

From the question given above, the following data were obtained:

Mass of Calcium (Ca = 10 g

Number of atom of Calcium (Ca) =?

The number of atoms present in 10 g of Ca be obtained as follow:

From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ atoms. This implies that 1 mole Ca contains 6.02×10²³ atoms.

1 mole of Ca = 40 g.

Now, if 40 g of Ca contains 6.02×10²³ atoms.

Therefore, 10 g of Ca will contain = (10 × 6.02×10²³) / 40 = 1.51×10²³ atoms.

Thus, 10 g of calcium contains 1.51×10²³ atoms.

Answer:

I believe its C but it could be B

Answer:A

Explanation:  i would say the first one

Answer:

Egypt

Explanation:

Hi again

Answer:Acceleration due to gravity on the moon is 1/6 times as that on the earth and we know that mass is property of the material it always remains same and weight is measure of gravitational force, hence

mass of object on moon is 60kg and weight =60g/6=10×10=100N

Explanation:

Mass of sample : 1987.5 g≈1990 g

Given

12% mass of Lithium chlorate

Required

Mass of sample

Solution

%mass = (mass of solute/mass of solution) x 100%

mass of solute = mass of Lithium chlorate = 238.5 g

Input the value :

12/100(0.12) = 238.5 g : mass of solution

mass of solution =238.5 : 0.12

mass of solution = 1987.5≈1990 g

x = = 0.50 M Answer:

In order to produce some SbCl5, a 1.00 mole sample of SbCl3 is first placed in an empty 2.00 liter container maintained at a temperature different from 182oC. At this temperature, Kc, equals 0.117. How many moles of Cl2 must be added to this container to reduce the number of moles of SbCl3 to 0.700 mole at equilibrium

Moles Cl2 that must be added = 0.40 mol

Explanation:

K = ( = 0.117

Equilibrium concentrations:

= (1.00 - 0.70) mol / 2.00 L = 0.15 M <<---why is it 1.00-0.70???

= 0.700 mole / 2.00L = 0.350 M

= x

Kc = ÷ (0.15) = 0.117

Moles Cl2 at equilibrium = 0.050 mol L x 2.00 L = 0.10 mol

Moles Cl2 needed to make 0.300 mol SbCl3 into SbCl5 = 0.30 mol

Moles Cl2 that must be added = 0.40 mol

Answer: 7.77 g/ml

Explanation:

Volume of cylinder with only water = 3.28 mL

Volume of cylinder with water and metal = 8.72 mL

Volume of metal = (Volume of cylinder with water and metal ) -(Volume of cylinder with only water)

=8.72-3.28

=5.44 ml

Mass of metal = 42.26 g

Formula of Density =  [tex]\dfrac{\text{Mass}}{\text{Volume}}[/tex]

i.e. the density of the metal = [tex]\dfrac{42.26}{5.44}\approx7.77\text{ g/ml}[/tex]

Hence, the density of metal = 7.77 g/ml

Answer:

b

Explanation:

Answer:

Q = 44.5 kJ

Explanation:

Given that,

Mass of water, m = 112 g

Water at 50.0°C cools to form ice at −45.0°C

We need to find the total amount of heat released. The formula for heat released is given by :

[tex]Q=mc\Delta T[/tex]

c is the specific heat of water, c = 4.184 J/g°C

So,

[tex]Q=112\times 4.184 \times (-45-50)\\\\Q=-44517.76\ J[/tex]

or

Q = -44.5 kJ

So, 44.5 kJ of heat is released.

Answer:

d. 9.95 × 10⁻³ mol

e. 249 g

f. 2.55 × 10²⁴ atoms

g. 4.32 × 10²² atoms

Explanation:

d. the number of moles of cobalt represented by 5.99 x 10²¹ cobalt atoms

We will use Avogadro's number: there are 6.02 × 10²³ atoms of cobalt in 1 mole of atoms of cobalt.

5.99 x 10²¹ atoms × 1 mol/6.02 × 10²³ atoms = 9.95 × 10⁻³ mol

e. the mass of 4.23 mol of cobalt

The molar mass of cobalt is 58.93 g/mol.

4.23 mol × 58.93 g/mol = 249 g

f. the number of cobalt atoms in 4.23 mol of cobalt

We will use Avogadro's number: there are 6.02 × 10²³ atoms of cobalt in 1 mole of atoms of cobalt.

4.23 mol × 6.02 × 10²³ atoms/1 mol = 2.55 × 10²⁴ atoms

g. the number of cobalt atoms in 4.23 g of cobalt

First, we will calculate the moles of cobalt using the molar mass of cobalt.

4.23 g × 1 mol/58.93 g = 0.0718 mol

Then, we will calculate the number of cobalt atoms using Avogadro's number.

0.0718 mol × 6.02 × 10²³ atoms/1 mol = 4.32 × 10²² atoms

Answer:

An ecosystem is a community or group of living organisms that live in and interact with each other in a specific environment.

Explanation:

That's the most straight forward explanation I could come up with

Answer:

20g or 0.2kg

Explanation:

this is because the mass of the powder is 20g and this will be added to the original mass of the milk causing it to increase by that amount

Answer: 20g

Explanation:

The ocean is not a part of Earth's layers.

Answer:

Ocean

Explanation:

Answer:

7.93 × 10⁻¹³ km/s

Explanation:

Step 1: Given data

Rate of growth of the fingernails (r): 2.50 cm/year

Step 2: Convert "r" from cm/year to km/year

We will use the following conversion factors.

[tex]\frac{2.50cm}{year} \times \frac{1m}{100cm} \times \frac{1km}{1000m} = 2.50 \times 10^{-5} km/year[/tex]

Step 3: Convert "r" from km/year to km/s

We will use the following conversion factors.

[tex]\frac{2.50 \times 10^{-5} km}{year} \times \frac{1year}{365day} \times \frac{1day}{24h} \times \frac{1h}{60min} \times \frac{1min}{60s} = 7.93 \times 10^{-13} km/s[/tex]

2.50 cm/year is equal to 7.93 × 10⁻¹³ kilometers/second.

Answer:

I would pipet 4 μl of each BSA work solution

Explanation:

To calculate the mass (in μg), we have to multiply the concentration C (in μg/ul) by the volume V (in μl):

C(μg/ul) x V( μl) = mass (μg)

We found the required volume for each solution, as follows:

5 μg/μl x V₁ = 20 μg ⇒ V₁ = 20 μg/(5 μg/μl ) = 4 μl

0.5 μg/μl x V₂ = 2 μg ⇒ V₂ = 2 μg/(0.5 μg/μl) = 4 μl

0.05 μg/μl x V₃ = 0.2 μg ⇒ V₃= 0.2 μg/(0.05 μg/μl) = 4 μl

Therefore, we need to pipet 4 μl of the solutions of concentrations 5μg/μl, 0.5 μg/μl, and 0.05 μg/μl to obtain the masses 20 μg, 2 μg, and 0.2 μg, respectively.

Answer:

See explanation below

Explanation:

There are several ways to know if an acid or base is strong. One method is calculating the pH. If the pH is really low, is a strong acid, and if it's really high is a strong base.

However we do not have a pH value here.

The other method is using bronsted - lowry theory. If an acid is strong, then his conjugate base is weak. Same thing with the bases.

Now, Looking at the 4 compounds, we can say that only two of them is weak and the other two are strong compounds. Let's see:

LiOH ---> Strong. If you try to dissociate :

LiOH ------> Li⁺ + OH⁻     The Li⁺ is a weak conjugate acid.

HF -----> Weak

HF --------> H⁺ + F⁻   The Fluorine is a relatively strong conjugate base.

HCl -----> Strong

This is actually one of the strongest acid.

NH₃ ------> Weak

Now writting the Ka and Kb expressions:

Ka = [H⁺] [F⁻] / [HF]

Kb = [NH₄⁺] [OH⁻] / [NH₃]

Finally, to calculate the [OH⁻] we need to use the following expression:

Kw = [H⁻] [OH⁻]

Solving for [OH⁻] we have:

[OH⁻] = Kw / [H⁺]

Remember that the value of Kw is 1x10⁻¹⁴. So replacing:

[OH⁻] = 1x10⁻¹⁴ / 7x10⁻⁶

[OH⁻] = 1.43x10⁻⁹ M

And now, multiplying by 10¹⁰ we have:

[OH⁻] = 1.429x10⁻⁹ * 1x10¹⁰

Hope this helps

Strong acids and bases are those which completely ionized in body fluid, and weak acids and bases are those who does not completely ionized in body fluid.

Ka expression is used to differentiate between strong and weak acids.

[tex]\bold{\dfrac{[H+][F-]}{[HF]}}[/tex]

[tex]\bold{\dfrac{[NH_4^+] [OH^-]}{[NH_3]} }[/tex]

Given, [tex]\bold{ [H^+]=1\times10^-^6\; at \;25^oC}[/tex]

We know, [tex]\bold{ [H^+]\times[OH^-]=1\times10^-^6\; at \;25^oC}[/tex]

[tex]\bold{[OH^-]=\dfrac{1\times10^-^1^4}{6.2\times10^-^6} = 1.43\times10^-^9}[/tex]

Now, multiplying the value by [tex]10^1^0[/tex]

[tex]\bold{( 1.429\times10^-^9) \times 1\times10^1^0= 14.29}[/tex]

Thus, the value is 14.29.

Learn more about acid and base, here:

https://brainly.com/question/10468518

Answer: the answer is C Aluminum cans get crushed before recycling.

Explanation:

Answer:

it will option C because it had no change in chemical reaction