List of top Chemistry Questions

For a first order reaction, the time required for completion of 90% reaction is ‘x’ times the half life of the reaction. The value of ‘x’ is (Given: In 10 = 2.303 and log 2 = 0.3010)

Choose the correct answer :

1. The minimum energy that must be possessed by photons in order to produce the photoelectric effect with platinum metal is

[Given The threshold frequency of platinum is 1.3 × 10¹⁵ s^–1 and h = 6.6 × 10^–34 Js.]

At 25°C and 1 atm pressure, the enthalpy of combustion of benzene (I) and acetylene (g) are –3268 kJ mol^–1 and –1300 kJ mol^–1, respectively. The change in enthalpy for the reaction 3C₂H₂(g) → C₆H₆(I), is

The Ksp for bismuth sulphide (Bi₂S₃) is 1.08 × 10^–73. The solubility of Bi₂S₃ in mol L^–1 at 298 K is

The correct order of electron gain enthalpies of Cl, F, Te and Po is

Given below are two statements.

Statement-I: During electrolytic refining, blister copper deposits precious metals.

Statement-II: In the process of obtaining pure copper by electrolysis method, copper blister is used to make the anode.

In the light of the above statements, choose the correct answer from the options given below.

Given below are two statements one is labelled as Assertion A and the other is labelled as Reason R:

Assertion A: The amphoteric nature of water is explained by using Lewis acid/base concept

Reason R: Water acts as an acid with NH3 and as a base with H₂S.

In the light of the above statements choose the correct answer from the options given below:

The number of bridged oxygen atoms present in compound B formed from the following reactions is

\(PB(NO_3)^2→(673 K)→A+PBO+O_2A→(Dimerise)B.\)

The metal ion (in gaseous state) with lowest spin-only magnetic moment value is

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Polluted water may have a value of BOD of the order of 17 ppm.

Reason R: BOD is a measure of oxygen required to oxidise both the bio-degradable and non-biodegradable organic material in water.

In the light of the above statements, choose the most appropriate answer from the options given below.

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: A mixture contains benzoic acid and naphthalene. The pure benzoic acid can be separated out by the use of benzene.

Reason R: Benzoic acid is soluble in hot water.

In the light of the above statements, choose the most appropriate answer from the options given below.

During halogen test, sodium fusion extract is boiled with concentrated HNO₃ to

Amongst the following, the major product of the given chemical reaction is

Amongst the following, the major product of

In the given reaction

In the given reaction ‘A’ can be

‘A’ can be

The major product formed in the following reaction, is

Which of the following ketone will NOT give enamine on treatment with secondary amines? [where t-Bu is –C(CH₃)₃]

An antiseptic Dettol is a mixture of two compounds ‘A’ and ‘B’ where A has 6π electrons and B has 2π electrons. What is ‘B’?

The correct order of reduction potentials of the following pairs is

(A)\( \frac{Cl_2}{Cl^–}\)

(B)\( \frac{I_2}{I^–}\)

(C) \(\frac{Ag^+}{Ag}\)

(D) \(\frac{Na^+}{Na}\)

(E) \(\frac{Li^+}{ Li}\)

Choose the correct answer from the options given below:

SO₂Cl₂ in reaction with an excess water results in the acidic mixture
SO₂CL₂+2H₂O\(\rightarrow\)H₂SO₄+2HCL
16 moles of NaOH is required for the complete neutralization of the resultant acidic mixture. The number of moles of SO₂Cl₂ used is

Which of the following sets of quantum numbers is not allowed?

The depression in the freezing point observed for a formic acid solution of concentration 0.5 mL L^–1 is 0.0405°C. Density of formic acid is 1.05 g mL^–1. The Van’t Hoff factor of the formic acid solution is nearly (Given for water k_f = 1.86 k kg mol^–1)

20 mL of 0.1 M NH₄OH is mixed with 40 mL of 0.05 M HCl.The pH of the mixture is nearest to(Given :K_b(NH₄OH) = 1×10^–5,log2 = 0.30,log3 = 0.48, log5 = 0.69,log7 = 0.84,log11 = 1.04)