A student performs an experiment in which 5.0 g of potassium chloride, KCI, are dissolved into 100.0 mL of distilled water. The student records the
temperature both before and after dissolving the KCl into the water, as shown in the data table below. Use this data to answer the question that follows.
Initial Temperature, °C Final Temperature, °C
21.8°C
16.4°C
Which statement below is a correct conclusion based on these results ?
The temperature of the water decreases and so the reaction is exothermic
The temperature of the water increases and so the reaction is exothermic
The temperature of the water decreases and so the reaction is endothermic
The temperature of the water increases and so the reaction is endothermic

Answer:

C) 4.

Explanation:

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In this case, since the electron configuration of nickel at its ground-state, considering 28 as its atomic number and the number of electrons it has in one atom, is:

[tex]Ni^{28}:1s^2,2s^2,2p^6,3s^2,3p^6,4s^2,3d^8[/tex]

We can see it has four energy levels, 1, 2, 3 and 4, which are related to the following principal quantum number, that describes the energy of an electron in the atom and its most probable distance with respect to the nucleus.

Therefore, nickel has C) 4 different principal quantum numbers.

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Answer:

1.58× 10²² atoms of Au

Explanation:

Given data:

Mass of gold = 5.18 g

Number of atoms of gold = ?

Solution:

First of all we will calculate the number of moles of gold.

Number of moles = mass/molar mass

Number of moles = 5.18 g/196.96 g/mol

Number of moles = 0.0263 mol

Number of atoms:

Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ atoms of Au

0.0263 mol × 6.022 × 10²³ atoms of Au / 1mol

0.158× 10²³ atoms of Au

1.58× 10²² atoms of Au

Answer:

a. The carbon-carbon bond in ethane's the longest!)

Explanation:

Ethane is a chemical compound that is organic in nature. Its chemical formula is [tex]$C_2H_6$[/tex]. It has two carbon atoms and six of hydrogen atoms that is connected to the carbon atoms.

Ethane is odorless and colorless at the standard temperature and standard pressure.

The carbon to carbon atoms in ethane is connected by a single bond.

The length of single carbon-carbon bond is greater than carbon-carbon double bond and triple bond.

Thus, carbon-carbon bond length in ethane is the longest.

Answer:

(C). Greater than 1atm

Explanation:

We are aware that water boils at 100 degree Celsius. Water can change its phase and become vapor at  100degree Celsius and at normal pressure which is 1atm.

In the given scenario we have enough temperature to convert water into vapor phase but we don't want it rather we want it to remain in liquid state. This can be achieved by increasing the pressure which was earlier required for vapor phase conversion. So the pressure should be greater than 1atm.

When we increase the temperature the molecules will get enough energy to escape into vapor phase, but when we will increase the pressure, it will provide hindrance to those molecules and will maintain them into Liquid state.

Answer:

See explanation

Explanation:

The boiling point of  a substance at a location depends mostly on the atmospheric pressure in that location. The lower the atmospheric pressure in a location, the lower the boiling point and vice versa.

Boiling point is defined as the temperature at which the vapor pressure of the liquid becomes equal to the atmospheric pressure.

In Denver (the mile high city), alcohol will boil at a lower temperature(due to its high altitude) than in Houston because pressure decreases with height.

The boiling point of alcohol in Houston and Denver will vary as a result of the difference in atmospheric pressure.

The boiling point of  a compound at a particular location depends on the

atmospheric pressure of that location. The lower the atmospheric pressure

of a given place or area, the lower the boiling point and vice versa.

In Denver (the mile high city), alcohol will boil at a lower temperature as a

result of its higher altitude than in Houston because atmospheric pressure

decreases with increase in height and vice versa.

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Explanation:

A chemical property of soda ash is, it is a alkaline compound

Answer: Results will tell you which hypothesis is true.

Explanation: The hypothesis becomes a theory if the results support it. d.A new experiment is designed to provide additional data about the hypothesis. Imagine that a team of scientists test a certain hypothesis, and the experimental results show that it is false. ... The results will show which other hypotheses must be true.

Answer:

Explanation:

The polarity of the 3 compounds would be in the order of

Ferrocene < Acetylferrocene < Diacetylferrocene

Your TLC data has to also support this observation . This can be checked by measuring the values of Rf ( Retention factor = distance travelled by solute/solvent ) .The Rf values also has to follow this particular order: -

Ferrocene > acetylferrocene > diacetylferrocene

2) Hexane happens to be a non-polar solvent. The polarity of hexane can be increased if some polar solvents for example, ethyl and methylene chloride etc are added

Therefore, in the increasing order of solvents polarity, we have

Hexane < 1:1 mixture of hexane: methylene chloride < 9:1 mixture of methylene chloride:

3) Chromatographic techniques all have a stationary phase in addition to a mobile phase. In the case of column chromatography, the silica gel will be the stationary phase and the solvent that will be poured will be the mobile phase.

4) The TLC and column chromatography both happen to have the same stationary phase which is the silica gel. Also, the same solvent mixture is used in both the techniques. This makes the result of the 2 to be almost the same. The difference seen between them is that, TLC works against the gravity while on the other hand column chromatography works in the direction of the gravity.

5) The key feature in the IR spectra of the acetylferrocene that will be absent in the spectra of ferrocene is the presence of carbonyl stretching frequency at close to 1700 per cm(cm-1). This peak is easily differentiated between both acetyl ferrocene and ferrocene.

Answer:

Explanation:

A, D,E and B i think is the correct answers  

Answer:

C

Explanation:

there is no explanation needed

Answer:

The value of ionization energy (IE) decreases down the group due to the increasing size as the valence electrons are more loosely bound. Thus lowest IE in this case is of Bi as it is bottom most element.

Explanation:

Answer:

0.767 moles of ammonium phosphate are produced

Explanation:

The reaction of ammona (NH3), with phosphoric acid is:

3 NH3 + H3PO4 → (NH4)3PO4

Where 3 moles of ammonia reacts per mole of H3PO4 to produce 1 mole of ammonium phosphate.

If 2.3 moles of ammonia reacts, the moles of ammonium phosphate produced if phosphoric acid is in excess are:

2.3 moles NH3 * (1 mole (NH4)3PO4 / 3 moles NH3) =

The change in internal energy (ΔΕ) of a system : -8 kJ

The laws of thermodynamics 1 state that: energy can be changed but cannot be destroyed or created  

The equation is:  

 [tex]\tt \Delta U=Q+W[/tex]

Energy owned by the system is expressed as internal energy (U)  

This internal energy can change if it absorbs heat Q (U> 0), or releases heat (U <0). Or the internal energy can change if the system does work or accepts work (W)  

The sign rules for heat and work are set as follows:  

• The system receives heat, Q +  

• The system releases heat, Q -  

• The system does work, W -  

• the system accepts work, W +  

5 kJ of work is done on the system : W = +5 kJ

releases 13 kJ of energy to the surroundings : Q = -13 kJ

[tex]\tt \Delta E=-13+5=-8~kJ[/tex]

Answer:

D) 2.8.18.7

Explanation:

because it has 7 valence electron that occupied by shells

Answer:

See explanation

Explanation:

Chlorine is a member of the halogen family known as a toxic yellowish green gas. Inhalation of chlorine for a prolonged period of time leads to  pulmonary edema. If a person comes in contact with compressed liquid chlorine the person may experience frostbite of the skin and eyes.

However chlorine is very useful in water disinfection and is preferred in water treatment because it provides residual disinfection of the treated water.

Chlorine gas may be dissolved in NaOH to form oxochlorate I which is used as a bleach in cleaning.

Answer:

Iodine

Explanation:

iodine is pretty good for you in moderation, iodine can ensure proper tyriod function but too much of it can cause thyroid gland inflammation and thyroid cancer, burning of the mouth, throat, and stomach; and coma.

Answer:

Yes

Explanation:

Answer:

The force exerted on it.

Explanation:

As the law of motion states, an object at rest will remain at rest an object in motion will remain in motion unless acted upon by another force.

Answer:

atomic number =17

mass number = 17+18= 35

Answer:

The center of the atom contains the nucleus so yes

Explanation:

Answer:

E = 5×10⁻¹⁹ J

Explanation:

Given data:

Wavelength = 400 nm (400×10⁻⁹ m)

Energy of wave = ?

Solution:

Formula:

E = h c/λ

c = 3×10⁸ m/s

h = 6.63×10⁻³⁴ Js

Now we will put the values in formula.

E = 6.63×10⁻³⁴ Js × 3×10⁸ m/s /400×10⁻⁹ m

E = 19.89×10⁻²⁶ J.m / 400×10⁻⁹ m

E = 0.05×10⁻¹⁷ J

E = 5×10⁻¹⁹ J

Answer:

Positive charge if there are more protons than electrons. Negative charge if there are more electrons than protons. If there's the same amount of protons and electrons, it's a neutral charge.

Explanation:

All matter is made up of electrons and protons. Electrons have a negative charge, protons have a positive charge. A charge is a type of particle measurement, and it is determined based on the amount of protons or electrons in a certain thing. The charge is which one there are more of, and there’s no charge (neutral) if they’re balanced.  

Answer: 10.73 g

Explanation:

2.3 mol Mg * (1 mol N2 / 3 mol Mg) * (14 g Mg / 1 mol g) = 10.73

Answer: 10

Explanation:

4Al + 2O2 --> 2Al2O3

This is the balanced equation so there are 2*2 +2*3 = 4+6 =10

Answer:

In a heterogeneous mixture, the parts of the mixture are noticeably different from one another. In a homogeneous mixture, the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another.

with what?..................

Answer:

maalat ang salt

Explanation:

Answer: 234.8 M

Explanation:

Answer:

FALSE.

Explanation:

The right answer is false. There are three different groups of phylum for worms.

Hope this helped!

Answer:

FALSE

there are like 3 different phylum

Explanation:

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