JEE Main entrance exam Question Bank Solutions for Chemistry (JEE Main)

The half-life of cobalt 60 is 5.26 years. The percentage activity remaining after 4 years is ______%.

A solution of a non-volatile solute in water freezes at −0.30°C. The vapour pressure of pure water at 298 K is 23.51 mm Hg and K_f for water is 1.86 degree/mol. The vapour pressure of rain solution at 298 K is ______ mm Hg.

Sulphide ion in alkaline solution reacts with solid sulphur to form polysulphide ions having formula, \[\ce{S^{2-}2}\], \[\ce{S^{2-}3}\], \[\ce{S^{2-}4}\], etc. if K₁ = 12 for \[\ce{S + S^{2-} <=> S^{2-}2}\] and K₂ = 132 for \[\ce{2S + S^{2-} <=> S^{2-}3}\], K₃ = ______ for \[\ce{S + S^{2-}2 <=> S^{2-}3}\].

The total number of α and β particles emitted in the nuclear reaction \[\ce{^238_92U -> ^214_82Pb}\] is ______.

The density of gold is 19 g/cm³. If 1.9 × 10^{−4 g} of gold is dispersed in one litre of water to give a sol having spherical gold particles of radius 10 nm, the number of gold particles per mm³ of the sol will be ______ × 10⁶.

The amount of C-14 isotope in a piece of wood is found to be 1/16^th of its amount present in a fresh piece of wood. The age of wood, half-life period of C-14 is 5770 years, is ______ years.

For which of the following K_p is less than K_c?

The weight of CO is required to form Re₂(CO)₁₀ will be ______ g, from 2.50 g of Re₂O₇ according to given reaction

\[\ce{Re2O7 + CO -> Re2(CO)10 + CO2}\]

Atomic weight of Re = 186.2; C = 12 and O = 16.

The equilibrium constant for the reaction is ______ × 10²⁶.

\[\ce{Fe + CuSO4 <=> FeSO4 + Cu}\] at 25°C.

Given `"E"_("Fe"//"Fe"^(2+))^0` = 0.44 V

`"E"_("Cu"//"Cu"^(2+))^0` = - 0.337 V

The rate of a first order reaction is 0.04 mol litre^-1 s^-1 at 10 minutes and 0.03 mol litre^-1 sec^-1 at 20 minutes after initiation. The half-life of the reaction is ______ min.

For the given first order reaction A → B the half life of the reaction is 0.3010 min. The ratio of the initial concentration of reactant to the concentration of reactant at time 2.0 min will be equal to ______. (Nearest integer)

A reaction has a half-life of 1 min. The time required for 99.9% completion of the reaction is ______ min.
(Round off to the nearest integer).
[Use: In 2 = 0.69; In 10 = 2.3]

The decomposition of N₂O₄ to NO₂ was carried out in chloroform at 280°C. At equilibrium, 0.2 mol of N₂O₄ and 2 × 10⁻³ mol of NO₂ were present in 2 ℓ of the solution. The equilibrium constant for the reaction \[\ce{N2O4 <=> 2NO2}\] is ______.

If the weight of the non-volatile solute urea (NH₂–CO–NH₂) is to be dissolved in 100 g of water, in order to decrease the vapour-pressure of water by 25%, then the weight of the solute will be ______ g.

Which of the following elements is considered a metalloid?

Elimination of bromine from 2-bromobutane results in the formation of ______.

The value of K_c is 64 at 800 K for the reaction \[\ce{N2(g) + 3H2(g) <=> 2NH3(g)}\].

The value of K_c for the following reaction is:

\[\ce{NH3(g) <=> 1/2N2(g) + 3/2H2(g)}\]

In which one of the following equilibria, K_P ≠ K_c?

A solid XY kept in an evacuated sealed container undergoes decomposition to form a mixture of gases X and Y at temperature T. The equilibrium pressure is 10 bar in the vessel. K_p for this reaction is ______.

In the reaction of oxalate with permanganate in an acidic medium, the number of electrons involved in producing one molecule of CO₂ is ______.