Mole Concept

Q. Two metallic oxides contain 27.6% and 30% oxygen respectively. If the formula of the first oxide is $X_3{O}_4$, the formula of the second will be:

1. $XO$
2. $X{O}_2$
3. $X_2{O}_5$
4. $X_2{O}_3$

Q.

Calculate the number of atoms in each of the following

(i) $\text{52 moles of Ar}$

(ii) $\text{52 u of He}$

(iii) $\text{52 g of He}$

Q. A mixture of gases contains $H_2$ and $O_2$ gases in the ratio of 1:4 by weight. What is the molar ratio of the two gases in the mixture?

1. 1:4
2. 16:1
3. 4:1
4. 2:1

Q. How many years would it take to spend one Avogadro’s number of rupees at a rate of 10 lakh of rupees in one second?

1. $8.65\times {10}^{18}$
2. $3.81\times {10}^4$
3. $1.91\times {10}^{10}$
4. $6.023\times {10}^{15}$

Q. A solution of ethanol in water is $10\%$ by volume. If density of the solution and pure ethanol are $0.9866$ g/mL and $0.785$ g/mL respectively, the mass percent will be:

1. $7.55\%$
2. $7.95\%$
3. $8.55\%$
4. $8.95\%$

Q. Calculate the mass of a formula unit of the complex $FeS{O}_4.7H_{2}O$ in unified atomic mass unit.

1. 230 u
2. 250 u
3. 278 u
4. 270 u

Q. The weight of a molecule of the compound $C_{60}{H}_{122}$ is

1. $1.4\times {10}^{-21}g$
2. $1.09\times {10}^{-21}g$
3. $5.025\times {10}^{23}g$
4. $16.023\times {10}^{23}g$

Q. In Carius method for estimation of halogens, 0.2 g of an organic compound gave 0.188 g of AgBr. The percentage of bromine (Nearest integer) in the compound is .

[Atomic mass: Ag = 108 u, Br = 80 u]

Q. What will be the molarity of a solution containing 5g of NaOH in 250 ml solution?

1. 0.1
2. 1
3. 0.5
4. 2

Q.

What is the molecular weight of sulfuric acid?

Q.

What is the atomic mass of Manganese?

Q.

What is the molar mass of calcium?

Q.

The charge on 1 g ions of $A{l}^{3+}$ is

1. 1/3 x N_Ae coulomb

2. 1/9 x N_Ae coulomb

3. 3 x N_Ae coulomb

4. 1/27 x N_Ae coulomb

Q. The number of neutrons in a drop of water (20 drops= $1\text{mL}$) at $4^{\circ }\text{C}$ is __________.

1. $6.023\times {10}^{22}$
2. $1.338\times {10}^{22}$
3. $6.023\times {10}^{20}$
4. $7.338\times {10}^{22}$

Q. In which case is number of molecules of water maximum?

1. 0.00224 L of water vapours at 1 atm and 273 K
   
2. 0.18 g of water
3. 18 mL of water
4. ${10}^{–3}$ mol of water

Q. One mole of oxygen gas at STP is equal to_____.

1. $6.022\times {10}^{23}$ molecules of oxygen
2. $6.022\times {10}^{23}$ atoms of oxygen
3. $16\text{g}$ of oxygen.
4. $32\text{g}$ of oxygen.

Q. Which of the following contains the greatest number of oxygen atoms?

1. 1 g of O
2. 1 g of $O_2$
3. 1 g of $O_3$
4. all have the same no of atoms.

Q. A gaseous mixture contains $C{O}_2\left(g\right)$ and $N_{2}O\left(g\right)$ in the ratio 2:5 by mass. The ratio of the number of molecules of $C{O}_2\left(g\right)$ and $N_{2}O\left(g\right)$ is:

1. 1:2
2. 5:4
3. 5:2
4. 2:5

Q. At ${90}^{\circ }C,$ pure water has
$\left[H_3{O}^{+}\right]={10}^{-6}mol{L}^{-1}.$ What is the value of $K_w$ at ${90}^{\circ }C?$

1. ${10}^{-6}$
2. ${10}^{-12}$
3. ${10}^{-14}$
4. ${10}^{-8}$

Q. A sample of impure cuprite, $C{u}_{2}O$, contains 66.6% copper. What is the percentage of pure $C{u}_{2}O$ in the sample?

1. 75%
2. 25%
3. 60%
4. 80%

Q. Number of moles of sulphur present in 1 mole of $H_{2}S{O}_4$ are?

1. $6.023\times {10}^{23}\text{moles of S}$
2. $1\text{mole of S}$
3. $4\text{moles of S}$
4. $2\text{moles of S}$

Q. The number of water molecules present in a drop of water (Volume $0.0018ml$) at room temperature is

1. $6.023\times {10}^{19}$
2. $1.084\times {10}^{18}$
3. $4.84\times {10}^{17}$
4. $5.023\times {10}^{23}$

Q.

The number of atoms present in one mole of an element is equal to Avogadros number. Which of the following element contains the greatest number of atoms?

(a) 4 g He

(b) 46 g Na

(c) 0.40 g Ca

(d) 12 g He

Q. Calculate the molecular mass of $N{H}_3$ molecule in grams.

1. $2.82\times {10}^{-24}$ g
2. $3.82\times {10}^{-23}$ g
3. $2.82\times {10}^{-23}$ g
4. $3.82\times {10}^{-24}$ g

Q. The density of liquid mercury is $13.6{\text{g cm}}^{-3}$. How many moles of mercury are there in 1 litre of the metal? (Atomic mass of $Hg=200$)

Q.

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

1. 1 : 4

2. 7 : 32

3. 1 : 8

4. 3 : 16

Q.

Calculate the molecular mass of MgCO₃.

Q.

What is the formula mass of ethyl alcohol, ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$?

Q. two pure liquids A and B have vapour pressures in the ratio 1:3. The mole fraction of A in vapour phase, when A and B are mixed in 1:3 molar ratio in a solution will be: a-0.1 b-0.2 c-0.3 d-0.5

Q. Haemoglobin contains 0.334 % of iron by weight. The molecular weight of haemoglobin is approximately 67200. The number of iron atoms (Atomic weight of $Fe$ is 56) present in one molecule of haemoglobin is:

1. 4
2. 6
3. 3
4. 2