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A first order reaction is 75% completed in 100minutes. How long will it take for it’s 87.5% completion? (a) 125 min (b) 150 min (c) 175 min (d) 200 min

After two half times 75% reaction is completed Hence, Half time = 50 minutes After three half times 87.5% reaction... View Article

Which of the following is not a pure substance? (a) Aerated water (b) Carbon dioxide (c) Oxygen (d) Zinc

Aerated drinks contain carbon dioxide (gas) as solute and water (liquid) as solvent. It is not a pure substance while... View Article

Balance the given reaction: Na + H₂O ——–> NaOH + H₂

Balancing chemical equation refers to balancing the stoichiometric coefficients on the reactants and products side. This must be done as... View Article

Pure ammonia is placed in a vessel at a temperature where it’s dissociation constant is appreciable. At equilibrium: (1) Kp does not change significantly with pressure (2) Degree of dissociation does not change with pressure (3) concentration of NH3 does not change with pressure (4) concentration of H2 is less than that of N2

Kp does not change significantly with pressure The equilibrium constant does not change if there is a change in concentrations,... View Article

Which is the monomer of neoprene in the following? (a) CH₂ = CH – C = CH (b) CH₂ = C (CH₃) – CH = CH₂ (c) CH₂ = C (Cl) – CH = CH₂ (d) CH₂ = CH – CH = CH₂

Chloroprene (CH2 = C (Cl) – CH = CH2) is the monomer of neoprene. Hence, the correct answer is option... View Article

Baking soda is a mixture of : (a) Sodium carbonate and acetic acid (b) Sodium carbonate and tartaric acid (c) Sodium hydrogen carbonate and tartaric acid (d) Sodium hydrogen carbonate and acetic acid

Baking powder is a mixture of sodium hydrogen carbonate and a mild edible acid such as tartaric acid. Hence, the... View Article

Convert propanoic acid into ethanoic acid?

Propanoic acid when reacts with an excess amount of ammonia gives propanamide. Propanamide on further reacting with bromine and potassium... View Article

Which of the following is not a simple tissue? (a)Parenchyma (b)collenchyma (c)xylem (d)sclerenchyma

Answer: (c) xylem Xylem is a complex tissue not a simple tissue. Xylem is a type of vascular tissue present in... View Article

Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below. (a) What will be the action of gas on (i) dry litmus paper? (ii) moist litmus paper? (b) Write a balanced chemical equation for the reaction taking place.

(a) When sulphur is heated in the presence of air, sulphur dioxide SO2 is formed. (i) Sulphur dioxide is a... View Article

The shape of ammonia molecules is: (A) Tetrahedral (B) Trigonal pyramid (C) Trigonal bipyramidal (D) Trigonal planar

Answer: (B) Trigonal pyramid The shape of the ammonia molecules is Trigonal pyramid or Distorted Tetrahedral. Also, read: Hybridization of... View Article

What happens when limestone is heated strongly?

When limestone is heated strongly, we get quick lime i.e CaO CaCO3 ⇌ CaO (s) + CO2 (s) Calcium oxide can be... View Article

What is the hybridization of sulphur dioxide?

In sulphur dioxide, the hybridization that takes place is sp2 type. To determine this, we will first look at the sulphur atom... View Article

Which among the following is not a base? (a) NaOH (b) KOH (c) NH₄OH (d) C₂H₅OH

Answer: (d) C2H5OH C2H5 OH is alcohol, not a base. An acid is any hydrogen-containing substance that is capable of donating... View Article

The rate at which a substance reacts depends upon its: (A) Active mass (B) Atomic mass (C) Molecular mass (D) Equivalent mass

Answer: (A) Active mass The law of mass action states that the rate of a reaction is proportional to the... View Article

Valency of oxygen is generally two whereas sulphur shows valency of two four and six. Explain.

Oxygen does not have vacant d-orbitals, so it cannot extend its valency beyond 2, but Sulphur shows valencies of 4... View Article

The molar heat capacity of water at constant pressure p is 75 JK-1 mol-1. When 1.0 kJ of heat is supplied to 100 g of water which is free to expand, the increase in temperature of water is:

Molar heat capacity = 75 JK-1 mol-1 18g of water = 1 mole = 75 JK-1 mol-1 q=1kJ=1000J Heat, q... View Article

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