Class 12th

A 10g mixture of hydrogen and helium is contained in a vessel of capacity 0.0125 m³ at 6 bar ansd $27°$ C. The mass of helium in the mixture is__________g. (nearest integer)

Borazine, also known as inorganic benzene, can be prepared by the reaction of 3-equivalents of “X” with 6-equivalents of “Y”. 'X' and “Y”, respectively are:

Reaction of BeCl₂ with LiAlH₄ gives:

(A) AlCl₃

(B) BeH₂

(C) LiH

(D) LiCl

(E) BeAlH₄

Choose the correct answer from options given below:

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

Assertion A: Phenolphthalein is pH dependent indicator, remains colourless in acidic solution and gives pink colour in basic medium.

Reason R: Phenolphthalein is a weak acid. It doesn't dissociate in basic medium.

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

A cylinder of fixed capacity of 44.8 litres contains helium gas at standard gas at standard temperature and pressure. The amount of heat needed to raise the temperature of gas in the cylinder by 20.0°C will be:

(Given gas constant R = 8.3 JK^-1 -mol^-1)

Which of the following can be used to prevent the decomposition of H₂SO₄?

Refining using liquation method is the most suitable for metals with:

Given two statements below:

Statement I : In Cl₂ molecules the covalent radius is double of the atomic radius of chlorine.

Statement II : Radius of anionic species is always greater than their parent atomic radius.

Choose the most appropriate answer from options given below:

A spherical of 1 kg mass and radius R is rolling with angular speed   $\omega$ on horizontal plane (as shown in figure). The magnitude of angular momentum of the shell about the origin O is $\frac{a}{3}{R}^2\omega .$  The value of a will be:

Match List I with List II:

Choose the correct answer from the options given below: