One mole of oxygen gas at STP is equal to:

(a)	6 .022× 1023 molecules of oxygen
(b)	6.022 × 1023 atoms of oxygen
(c)	16 g of oxygen molecule
(d)	32 g of oxygen

Choose the correct answer from the option given below: 

1. (a) and (b)
2. (a) and (c)
3. (a) and (d)
4. (c) and (d)

Sulphuric acid reacts with sodium hydroxide according to the reaction:

${\mathrm{H}}_2{\mathrm{SO}}_4+2\mathrm{NaOH}\to {\mathrm{Na}}_2{\mathrm{SO}}_4+2{\mathrm{H}}_2\mathrm{O}$

When 1L of 0.1 M sulphuric acid solution is allowed to react with 1 L of 0.1 M sodium hydroxide solution, the amount of sodium sulphate formed and its molarity in the solution obtained are respectively-

When 50.0 kg of nitrogen gas (N₂) and 10.0 kg of hydrogen gas (H₂) are combined, what is the quantity of ammonia gas (NH₃) produced?

1. 33.0 ×10³ mol

2. 56.1×10³ g

3. 6.5 ×10³ g

4. None of the above

A solution is prepared by adding 2 g of substance A to 18 g of water. The mass percent of the solute is:

1. 20%

2. 10%

3. 15%

4. 18%

Find the mass of NaNO₃ required to prepare 50 mL of aqueous solution containing 70.0 mg Na⁺ per mL.
(Round off to the nearest integer.
Given: Na = 23, N = 14, O = 16)

Find the mass of CaCO₃ required to completely react with 25 mL of 0.75 M HCl according to the reaction:

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + CO₂(g) + H₂O(l)

1. 0.36 g

2. 0.09 g

3. 0.96 g

4. 0.66 g

How many significant figures are present in the following numbers?

1. 3, 3, 3
2. 3, 4, 3
3. 3, 2, 3
4. 3, 4, 4

An aqueous solution contains 18 g of urea in 1500 cm³ of solution.
If the density of the solution is 1.052 g cm⁻³ and the molar mass of urea is 60 g mol⁻¹,
calculate the molality of the solution.
1. 0.2
2. 0.192
3. 0.064
4. 1.2

Percentage of C, H & N in a compound is given as follows:
C=40%; H=13.33%; N=46.67%

The empirical formula of the compound will be:
1. $C{H}_{2}N$
2. $C_2{H}_{4}N$
3. $C{H}_{4}N$
4. $C{H}_{3}N$