What is the approximate number of atoms present in 4.25 grams of NH₃?

1. 4 x 10²³ 

2. 2 x 10²³ 

3. 1 x 10²³ 

4. 6 x 10²³ 

In the reaction, 4NH₃(g)+ 5O₂(g) $\to$4NO(g) +6H₂O(l)

When 1 mole of ammonia and 1 mole of O₂  reacts to completion, then:

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: 

0.24g of a volatile gas, upon vaporisation, gives 45 mL vapour at NTP. What will be the vapour density of the substance?

(Density of H₂ = 0.089)

1. 95.93

2. 59.93

3. 95.39

4. 5.993

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

2. 1.4

3. 1.8

4. 1.6

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