Some Basic Concepts of Chemistry

The number of hydrogen atoms present in 5.4 g of urea is : (Given : Molar mass of urea : 60 g mol-1, NA : 6.022 × 1023 particles mol-1)

1. 2.168 × 1022
2. 2.168 × 1023
3. 1.084 × 1022
4. 1.084 × 1023

The numbers 17.0145 and 21.0235 were rounded to three figures after the decimal point. The resulting numbers, respectively, are

1. 17.015 and 21.024
2. 17.014 and 21.023
3. 17.015 and 21.023
4. 17.014 and 21.024

The amount of carbon dioxide evolved upon complete combustion of 116 g of n-butane is (Given: atomic mass in amu H = 1, C = 12 and O = 16)

1. 362 g
2. 352 g
3. 322 g
4. 176 g

Among the following, choose the ones with equal number of atoms. Choose the correct answer from the options given below:

1. B, C, and D only
2. B, D, and E only
3. A, B, and C only
4. A, B, and D only

Dalton's Atomic theory could not explain which of the following?

1. Law of multiple proportion
2. Law of gaseous volume
3. Law of conservation of mass
4. Law of constant proportion

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

1. 750 mg
2. 250 mg
3. Zero mg
4. 200 mg

The highest number of helium atoms is in

1. 4 mol of helium
2. 4u of helium
3. 4 g of helium
4. 2.271098 L of helium at STP

A compound X contains 32\% of A, 20\% of B and remaining percentage of C. Then, the empirical formula of X is : (Given atomic masses of A=64 ; B=40 ; C=32 u)

1. A2BC2
2. ABC3
3. AB2C2
4. ABC4

The amount of glucose required to prepare 250 mL of M20 aqueous solution is : (Molar mass of glucose : 180 g mol-1)

1. 2.25 g
2. 4.5 g
3. 0.44 g
4. 1.125 g

1.0 g of H2 has same number of molecules as in:

1. 14 g of N2
2. 18 g of H2O
3. 16 g of CO
4. 28 g of N2