An element X has the following isotopic composition,

²⁰⁰X : 90%, ¹⁹⁹X : 8.0%, ²⁰²X : 2.0%

The weighted average atomic mass of the naturally occurring element X is closest to: 

1.	205 u	2.	220 u
3.	196 u	4.	200 u

Calculate the vapour density of a volatile gas if 0.24 g of the gas produces 45 mL of vapour at NTP.
(Given that the density of hydrogen at STP is 0.08988 g L⁻¹).

1. 95.93

2. 59.93

3. 95.39

4. 69.93

The hydrated salt, Na₂SO₄.nH₂O, undergoes a 55% loss in mass on heating and becomes anhydrous. The value of n will be:

12 g of Mg (atomic mass = 24) will react completely with an acid to yield:

1. One mole of H₂ 

2. A half mole of H₂

3. One mole of O₂

4. None of the above

The molality of a 15% (w/vol.) solution of H₂SO₄ of density 1.1g/cm³ is:

1. 1.2 mol/kg

2. 1.4 mol/kg

3. 1.8 mol/kg

4. 1.6 mol/kg

Which mode of expressing concentration is independent of temperature?

1. Molality

2. Percent by mass

3. Mole fraction

4. All of the above 

The product of atomic mass and specific heat of metal is approximately 6.4. This was given by:

1. Dalton's law

2. Avogadro's law

3. Newton's law

4. Dulong Petit's law

A metal M forms a compound M₂HPO₄. The formula of the metal sulphate is:

1. M₂SO₄ 

2. MSO₄

3. M(SO₄${)}_2$

4. M₂(SO₄)₃

A partially dried clay mineral contains 8% water. The original sample contained 12% water and 45% silica. The percentage of silica  in the partially dried sample is nearly:

Which of the following represents the correct order of mass fractions (ω) of gases
when 1 L of N₂, 7/8 L of O₂, and 1 L of CO are mixed under identical conditions of temperature and pressure?

1. ${\mathrm{\omega }}_{{\mathrm{N}}_2}={\mathrm{\omega }}_{{\mathrm{O}}_2}>{\mathrm{\omega }}_{\mathrm{CO}}$ 

2. ${\mathrm{\omega }}_{{\mathrm{N}}_2}={\mathrm{\omega }}_{\mathrm{CO}}>{\mathrm{\omega }}_{{\mathrm{O}}_2}$ 

3. ${\mathrm{\omega }}_{{\mathrm{N}}_2}={\mathrm{\omega }}_{{\mathrm{O}}_2}={\mathrm{\omega }}_{\mathrm{CO}}$

4. ${\mathrm{\omega }}_{\mathrm{CO}}>{\mathrm{\omega }}_{{\mathrm{N}}_2}>{\mathrm{\omega }}_{{\mathrm{O}}_2}$