1. The highest number of helium atoms is in

(1).4 g of helium

(2). 2.271098 L of helium at STP

(3). 4 mol of helium

(4). 4 u of helium

2. 1 gram of sodium hydroxide was treated with 25mL of 0.75 M HCl solution, the mass of sodium hydroxide left unreacted is equal to

(1).Zero mg

(2). 200 mg

(3). 750 mg

(4). 250 mg

3. A compound X contains 32 % of A, 20 % of B₂ and remaining percentage of C. Then, the empirical formula of X is:

(1).\(\text{AB}_2\text{C}_2\)

(2). \(\text{ABC}_4\)

(3). \(\text{A}_2\text{BC}_2\)

(4). \(\text{ABC}_3\)

4. Among the following, choose the ones with equal number of atoms.
A. 212 g of \(Na_2 CO_3 \left(s\right)\) [molar mass = 106 g]B. 248 g of\( Na_2 O \left(s\right)\) [molar mass = 62 g]C. 240 g of \(NaOH \left(s\right)\) [molar mass = 40 g]D. 12 g of \(H_2 \left(g\right)\) [molar mass = 2 g]E. 220 g of \(CO_2 \left(g \right) [molar mass = 44 g]
Choose the correct answer from the options given below :

(1).(1) B, D, and E only

(2). (2) A, B, and C only

(3). (3) A, B, and D only

(4). (4) B, C, and D only