BASIC CONCEPTS JEE

Number of atoms in the following samples of substances is the largest in :

• 127.0g of iodine

• 48.0g of magnesium

• 71.0g of chlorine

• 4.0g of hydrogen

The ratio of mass percent of C and H of an organic compound (C_xH_yO_z) is 6 : 1. If one molecule of the above compound ( C_xH_yO_Z ) contains half as much oxygen as required to burn one molecule of compound C_XH_Y completely to CO₂ and H₂O. The empirical formula of compound C_xH_yO_z is :

• C₂H₄O

• C₃H₄O₂

• C₂H₄O₃

• C₃H₆O₃

The concentrated sulphuric acid that is peddled commercially is 95% H₂SO₄ by weight. If the density of this commercial acid is 1.834 g cm^-3, the molarity of this solution is :-

(1) 17.8 M

(2) 15.7 M

(3) 10.5 M

(4) 12.0 M

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The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecule is :

(1) 1 : 8

(2) 3 : 16

(3) 1 : 4

(4) 7 : 32

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3g of activated charcoal was added to 50 mL of acetic acid solution (0.06N) in a flask. After an hour it was filtered and the strength of the filtrate was found to be 0.042 N. The amount of acetic acid adsorbed (per gram of charcoal) is :

(1) 42 mg

(2) 54 mg

(3) 18 mg

(4) 36 mg

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The density of a solution prepared by dissolving 120 g of urea (mol. mass = 60 u) in 1000 g of water is 1.15 g/mL. The molarity of this solution is

(1) 2.05 M

(2) 0.50 M

(3) 1.78 M

(4) 1.02 M

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The ratio of number of oxygen atoms (O) in 16.0g oxygen (O), 28.0 g carbon monoxide (CO) and 32.0g oxygen (O₂) is :

(Atomic mass :C =12, O =16 and Avogadro’s constant N_A = 6.0 * 10²³ mol^-1)

(1) 3 : 1 : 1

(2) 1 : 1 : 2

(3) 3 : 1 : 2

(4) 1 : 1 : 1

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When CO₂ (g) is passed over red hot coke it partially gets reduced to CO(g). Upon passing 0.5 litre of CO₂ (g) over red hot coke, the total volume of the gases increased to 700 mL. The composition of the gaseous mixture at STP is :

(1) CO₂ = 200 mL: CO = 500mL

(2) CO₂ = 350 mL: CO = 350mL

(3) CO₂ = 0.0 mL: CO = 700mL

(4) CO₂ = 300 mL: CO = 400mL

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An open vessel at 300 K is heated till ⅖ th of the air in it is expelled. Assuming that the volume of the vessel remains constant, the temperature to which the vessel is heated is :

(1) 750 K

(2) 400 K

(3) 500 K

(4) 1500K

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The density of 3M solution of sodium chloride is 1.252 g mL^-1. The molality of the solution will be (molar mass, NaCl = 58.5 g mol^-1)

(1) 2.18 m

(2) 3.00 m

(3) 2.60 m

(4) 2.79 m

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