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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

1mol of CH₄ contains?

A. 6.02 × 1023 atoms of H B. 4g atom of hydrogen C. 1.81 × 1023 molecules of CH4 D. 3.0g of carbon Solution: (B) 1 mole of... View Article

A molar solution is one that contains one mole of solute in:

A. 100 ml of solvent B. 1000 g of solvent C. 1 liter solution D. 22.4 liter of solution Solution: (C) By definition, one molar solution... View Article

Crystals of which pair are isomorphous?

A. ZnSO4, SnSO4 B. MgSO4, CaSO4 C. ZnSO4, MgSO4 D. PbSO4, NiSO4 Solution: (A) ZnSO4 crystal is Orthorhombic SnSO4 crystal is... View Article

In known elements, the maximum number is of;

A. Metals B. Non-metals C. Metalloids D. None of these Solution: (A) If we look at the mordern periodic table, there are about a total... View Article

Number of molecules in 100 ml of each of O₂ NH₃ and CO₂ at STP are in the order:

A. CO2 > O2 > NH3 B. NH3 > O2 > CO2 C. All are equal D. NH3 = CO2 > O2 Solution: (C) As per Avogadro's law, if the... View Article

What will the atomic weight of metal be? Given, the vapour density of a metal chloride is 6.6 and its oxide contains 53% metal.

A. 21 B. 54 C. 27.06 D. 2.086 Solution: (C) VD of metal chloride = 66 To find, the atomic mass of metal. Let the weight of metal... View Article

If 10²¹ molecules are removed from 200 mg of CO₂, the number of moles of CO₂ left is:

A. 2.88 × 10−3 B. 28.8 × 10−3 C. 0.288 × 10−3 D. 1.66 × 10−3 Solution: (A) Molar mass... View Article

Which out of the following is not a homogeneous mixture?

A. Smoke B. Air C. Brass D. Aqueous solution of sugar Solution: (A) If we recall the definition of homogeneous solutions, these are... View Article

Calculate the number of moles in 1m³ gas at STP.

A. 4.46 B. 44.6 C. 446 D. 4460 Solution: (B) 1m3 = 1000 L At STP volume of 1 mol = 22.7 L Therefore, n (no. of moles) in 1m3 = 1000... View Article

An organic compound made of C, H and N contains 20% nitrogen. Its molecular weight is:

A. 70 B. 140 C. 100 D. 65 Solution: (A) The atomic mass of nitrogen = 14 Since the compound contains C, H and N, at least one N atom... View Article

In an experiment, 4 gm of M₂Ox oxide was reduced to 2.8 gm of the metal. If the atomic mass of the metal is 56 gm/mol, the number of oxygen atoms in the oxide is:

A. 1 B. 2 C. 3 D. 4 Solution: (C) 1 Mol M2Ox = (2 x 56 + 16 x) gm Now we consider, (2 x 56 + 16 x) of oxide = 112 gm metal... View Article

If the components of air are N₂ 78%, O₂ 21%; Ar 0.9% and CO₂ 0.1% by volume, what will be the molecular weight of air?

A. 28.9 B. 32.4 C. 16.4 D. 14.5 Solution: (A) Avg molar mass of air = (28×78+32×21+40×0.9+44×0.1) / 100 = 28.93... View Article

An organic compound containing C, H and N gave the following analysis: C = 40%; H = 13.33%; N = 46.67%. Its empirical formula would be;

A. C2H2N B. C3H7N C. CH4N D. CHN Solution: (C) Element % by mass Atomic mass Relative number of... View Article