Avogadro's Law & Gay Lussac's Law

Q.

Define STP and NTP ?

Q. When $3.00g$ of a substance $X$ is dissolved in $100g$ of $CC{l}_4$, it raises the boiling point by 0.60 K. The molar mass of the substance $X$ in $g{\text{mol}}^{-1}$. (Nearest integer) is
[Given $K_b$ for $CC{l}_4$ is $5.0Kkg{\text{mol}}^{-1}$ ]
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Q.

A sample of ${\mathrm{CaCO}}_3$has $\mathrm{Ca}=40\%,\mathrm{C}=12\%\mathrm{and}\mathrm{O}=48\%$. If the law of constant proportions is true, then the weight of Calcium in $4\mathrm{g}$ of a sample of calcium carbonate from another source will be:

1. $0.016\text{g}$

2. $0.16\mathrm{g}$

3. $1.6\text{g}$

4. $16\text{g}$

Q. For an aqueous solution freezing point is – ${0.186}^{\circ }C$. Elevation of the boiling point of the same solution is ($K_f$ =1.86 $mol{e}^{-1}$ kg and $K_b$ = 0.512 $mol{e}^{-1}$ kg)

1. ${0.512}^{\circ }C$
2. ${51.2}^{\circ }C$
3. ${5.12}^{\circ }C$
4. ${0.0512}^{\circ }C$

Q. As 1.Temperature is directly proportional to pressure
2.Pressure is inversely proportional to Volume

But in summers, let us say at 45^oC if we fill air in tyres of bikes, as the temperature is high, pressure should be high and when pressure becomes high, volume should decrease!

But this does not happen!

Why?

Q.

$5.1gN{H}_{4}SH$ is introduced in 3.0 L evacuated flask at ${327}^{o}C$. 30% of the solid$N{H}_{4}SH$ decomposed to $N{H}_{3}and{H}_{2}S$ as gases. The $K_P$ of the reaction at ${327}^{o}C$ is
$(R=0.082Latmmo{l}^{-1}$,
molar mass of $S=32gmo{l}^{-1}$,
molar mass $N=14gmo{l}^{-1}.$

1. $1\times {10}^{-4}at{m}^2$

2. $4.9\times {10}^{-4}at{m}^2$

3. $0.242at{m}^2$

4. $0.242\times {10}^{-4}at{m}^2$

Q. If the pressure of the gas contained in a closed vessel is increased by $20\%$ when heated by $273K$ then, its initial temperature must have been:

1. ${1052}^{\circ }\text{C}$
2. $1029\text{K}$
3. ${1365}^{\circ }\text{C}$
4. $1365\text{K}$

Q. A 1 molal $K_{4}Fe(CN{)}_6$ solution has a degree of dissociation of 0.4. Its boiling point is equal to that of another solution which contains 18.1 weight per cent of a nonelectrolyte solute A. The molar mass of A in $g/mol$ is (Round off to the Nearest Integer)

Q. If $v$ is the volume of one molecule of a gas under given conditions, then van der Waals constant 'b' is : ($N_0$ = Avogadro's number)

1. $4v$
2. $\frac{N_0}{4v}$
3. $\frac{4v}{N_0}$
4. $4v{N}_0$

Q. The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecule is:

1. 1 : 8
2. 3 : 6
3. 1 : 4
4. 7 : 32

Q. The density of oxygen is $1.43g{L}^{-1}$ at STP. The density of oxygen at ${17}^{\circ }\text{C}$ and $800torr$ is:

1. $1.417{\text{g L}}^{-1}$
2. $4.4{\text{g L}}^{-1}$
3. $0.5{\text{g L}}^{-1}$
4. $5.728{\text{g L}}^{-1}$

Q.

How many moles of electrons weigh one kilogram? (Mass of electron $=9.108\times {10}^{-31}kg$, Avogadro’s number $=6.023\times {10}^{23}$)

1. $6.023\times {10}^{23}$
2. $\frac{1}{9.108}\times {10}^{31}$
3. $\frac{6.023}{9.108}\times {10}^8$
   
4. $\frac{1}{9.108\times 6.023}\times {10}^8$

Q.

What does the R stand for in the ideal gas law $\mathrm{pV}=\mathrm{nRT}$?

Q.

Write the balanced chemical reaction for the combustion of benzene (${\mathrm{C}}_6{\mathrm{H}}_6$) .

Q. A gas cylinder containing cooking gas can withstand a pressure of 14.9 atmospheres. The pressure gauge of the cylinder indicates that the pressure at ${27}^{\circ }$C is 12 atmospheres. Due to sudden fire in the building, the temperature starts rising. The temperature at which the cylinder explodes is

1. 200°C
2. 123.8°C
3. 67.3°C
4. 99.5°C

Q. Why is Dalton's law of partial pressure not applicable to NH3 and HCl?

Q. The number of chlorine atoms in 20 mL of chlorine gas at STP is $x\times {10}^{21}$. The value of x (Rounded off to the Nearest integer) is
.
[Assume chlorine is an ideal gas at STP,
$N_A=6.023\times {10}^{23}$]

Q. On mixing 10 ml of ethanol with 10 ml of benzene the total volume of the solution is (1) > 20 ml (2) < 20 ml (3) = 20 ml (4) Cant be predicted r

Q.

The temperature of a gas placed in an open container is raised from ${27}^{\circ }to{227}^{\circ }C.$ The percent of the original amount of the gas expelled from the container will be ?

1. 20

2. 40

3. 60

4. 80

Q.

What will be the molar volume of nitrogen and argon at 273.15 K and 1 atm?

Q. Two separate bulbs contain ideal gases A and B. The density of gas A is twice that of gas B. The molecular mass of A is half that of gas B. The two gases are at the same temperature. The ratio of the pressure of A to that of gas B is

1. 1/2
2. 4
3. 2
4. 1/4

Q.

An ideal gas expands against a constant external pressure of 2 atmosphere from 20L to 40L and absorbs 10kJ of heat from surrounding. What is the change in the internal energy of the system ?

Q. A gas mixture of 3 litres of propane $\left(C_3{H}_8\right)$ and butane $\left(C_4{H}_{10}\right)$ on complete combustion at ${25}^o$ produced 10 litre $C{O}_2.$ Find out the composition of gas mixture (Propane : Butane)

1. $3:1$
2. $1:2$
3. $2:1$
   
4. $1:1$

Q.

A cylinder containing cooking gas can withstand a pressure of 15 atm. The pressure gauge of the cylinder indicates 12 atm at ${27}^{\circ }C$. Due to a sudden fire in the building, the temperature starts rising. At what temperature will the cylinder explode?

1. 

2. 

3. 

4. 

Q.

Derive the ideal gas equation on the basis of the laws of Boyle, Charles, and Avogadro. Calculate the volume occupied by an ideal gas at STP, if 0.25 L of the gas is present at a pressure of 700 mm of Hg and 273℃.

Q.

State and explain ideal gas law?

Q.

If the ratio by mass of magnesium and sulphur is $3:4$ in Magnesium sulphide, then what is the ratio of the number of magnesium and sulphur atoms?

Q. Two closed vessel $A$ and $B$ of equal volume containing air at pressure $P_1$ and temperature $T_1$ are connected to each other through a narrow open tube. If the temperature of one is now maintained at $T_1$ and other at $T_2$ (where $T_1>T_2$) then that what will be the final pressure?

1. $\frac{T_1}{2P_1{T}_2}$
2. $\frac{2P_1{T}_2}{T_1+T_2}$
3. $\frac{2P_1{T}_2}{T_1-T_2}$
4. $\frac{2P_1}{T_1+T_2}$

Q. According to Avogadro's hypothesis, two samples of gas of equal volume, at the same temperature and pressure, contain the same number of molecules. But is there any proof of this? We can't possibly count the total molecules in two different gases of equal volumes at equal temperature and pressure. Then how did we arrive at this hypothesis? If not experemental, is there any Mathematical proof of this statement?

Even the exact number of atoms or molecules in 1 mole of any substance is known and is termed as Avogadro's Number. How was is found? How did we know the exact number of molecules present in 1 mole of a substance? Please provide the derivation if any.

Q.

The pressure p of a gas is plotted against its absolute temperature T for two different constant volumes, $V_1$ and $V_2$. When $V_1>V2$ , the

1. Curves have the same slope and do not intersect

2. Curves must intersect at some point other than T=0

3. Curve for has a greater slope than that for

4. Curve for has a greater slope than that for