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2.6 g of a mixture of calcium carbonate and magnesium carbonate is strongly heated to the constant weight of 1.3 g. The atomic weights of calcium and magnesium are 40 and 24 respectively. State which of the following weights expresses the weight of calcium carbonate in the original mixture?

A. 980 mg B. 400 mg C. 1.75 g D. 0.74 g Solution: (D) Let the weight of CaCO3 in mixture = x g Then weight of MgCO3 will be 2.6-x g... View Article

4.0g of caustic soda (molmass40) contains the same number of sodium ions as present in?

A. 10.6 g of Na2CO3 (mol.mass 106) B. 58.5g of NaCl (formula mass 58.5) C. 100ml of 0.5MNa2SO4 (formula mass 142) D. 1mol of NaNO3... View Article

If isotopic distribution of C-12 and C-14 is 98% and 2% respectively, then the number of C-14 atoms in 12 g of carbon is;

A. 1.032 × 1022 B. 3.01 × 1022 C. 5.88 × 1023 D. 6.02 × 1023 Solution: (A) 1 mole of carbon has NA molecules.... View Article

If 224 mL of a triatomic gas has a mass of 1 g at 273 K and 1 atm pressure, then the mass of one atom is;

A. 8.30 × 0−23 g B. 6.24 × 10−23 g C. 2.08 × 10−23 g D. 5.54 × 10−23 g Solution: () No.... View Article

Among the following pairs of compounds, the one that illustrates the law of multiple proportions is:

A. NH3 and NCl3 B. H2S and SO2 C. CuO and Cu2O D. CS2 and FeSO4 Solution: (C) If we recall the concept of law of multiple proportions... View Article

Assuming fully decomposed, the volume of CO₂ released at STP on heating 9.85 g of BaCO₃ (Atomic mass of Ba = 137) will be _____.

A. 0.84 L B. 2.24 L C. 4.06 L D. 1.12 L Solution: (D) BaCO3 → BaO + CO2↑ Molecular weight of BaCO3 = 137 + 12 + (3 x 16)... View Article

The amount of zinc required to produce 224 mL of H₂ at STP on treatment with dilute H₂SO₄ will be;

A. 65 g B. 0.065 g C. 0.65 g D. 6.5 g Solution: () The reaction between zinc with sulfuric acid is given by the following formula. Zn... View Article

Dimensions of pressure are same as that of;

A. Energy B. Energy per unit volume C. Force D. Force per unit volume Solution: (B) Dimension of Pressure, Pressure = F / A ⇒... View Article

Two containers P and Q of equal volume (1 litre each) contain 6 g of O₂ and SO₂ respectively at 300 K and 1 atmosphere, then;

A. Number of molecules in P is less than that in Q B. Number of molecules in P and Q is same C. Number of molecules in Q is less than that... View Article

Rearrange the following (I to IV) in the order of increasing masses and choose the correct answer from (a), (b) ,(c) and (d) (Atomic mass :N = 14, O = 16, Cu = 63).

I. 1 molecule of oxygen II. 1 atom of nitrogen III. 1 × 10-10 g molecular weight of oxygen IV. 1 × 10-10 g atomic weight of... View Article

How many millilitres (mL) of 1 M H₂SO₄ solution is required to neutralise 10 mL of 1 M NaOH solution?

A. 2.5 B. 5.0 C. 10.0 D. 20.0 Solution: (B) The reaction is, H2SO4 + 2NaOH → Na2SO4+ 2H2O Using normality, 2 × MH2SO4... View Article

0.115 g of pure sodium metal was dissolved in 500 ml distilled water. The normality of the above solution, whose resulting volume is 400 ml, would be;

A. 0.010 N B. 0.0115 N C. 0.0125 N D. 0.046 N Solution: (A) Weight of solute = 0.115 g The molecular mass of solute = 23 The volume... View Article

A 5 molar solution of H₂SO₄ is diluted from 1 litre to a volume of 10 litres, the normality of the solution will be;

A. 1 N B. 0.1 N C. 5 N D. 0.5 N Solution: () N1V1 = N2V2 Given, molarity of H2SO4 = 5M, N1 = Molarity × basicity = 5 ×... View Article

A metal (M) sulphate contains 9.87% of M. It is an isomorphous sulphate with ZnSO₄.7H₂O. What will the atomic weight of M be;

A. 40.3 B. 36.3 C. 24.3 D. 11.3 Solution: (C) Let x = at the mass of M S = 32 4O = 64 7H2O = 126 Thus, MSO4 molecular mass = x... View Article

The molecular weight of O₂ and SO₂ are 32 and 64 respectively. At 15^oC and 150 mm Hg pressure, one litre of O₂ contains ‘N’ molecules. The number of molecules in two litres of SO₂ under the same conditions of temperature and pressure will be:

A. N/2 B. N C. 2N D. 4N Solution: (C) If we recall Avogadro's law it states,"equal volumes of all gases contain equal number of... View Article

Boron has two stable isotopes, 10B(19%) and 11B(81%). The atomic mass that should appear for boron in the periodic table is

A. 10.8 B. 10.2 C. 11.2 D. 10.0 Solution: (B) Average atomic weight = ∑% abundant × atomic mass / 100 = (19 × 10) +... View Article

Ratio of C_p and Cv of a gas ‘X’ is 1:4. The number of atoms of the gas ‘X’ present in 11.2 L of it at NTP will be;

A. 6.02 × 1023 B. 1.2 × 1023 C. 3.01 × 1023 D. 2.01 × 1023 Solution: (A) Ratio of Cp/CV for the gas X = 1:4... View Article

A metal oxide has the formula Z₂O₃. It can be reduced by hydrogen to give free metal and water. 0.1596 g of the metal oxide requires 6 mg of hydrogen for complete reduction. The atomic weight of the metal is;

A. 27.9 B. 159.6 C. 79.8 D. 55.8 Solution: (D) Z2O3 + 3H2 → 2Z + 3H2O 1 mole of the metal requires 3 moles of H2 for complete... View Article

1 c.c. of N₂O at NTP contains:

A. 1.8 / 224 × 1022 atoms B. 6.02 / 22400 × 1023 molecules C. 1.32 / 224 × 1023 electrons D. All of the above Solution:... View Article

The density of gas A is three times that of gas B. If the molecular weight of A is M, the molecular weight of B is;

A. 3M B. √3M C. M / 3 D. M / √3 Solution: (C) d ∝ M ⇒ d1 / d2 = M1 / M2 3d / d = M / M2 M2 = M / 3... View Article