Class 11th

Which among the following species has unequal bond lengths?

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

Assertion A : When a rod lying freely is heated, no thermal stress is developed in it.

Reason R : On heating, the length of the rod increases.

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

The pitch of the screw gauge is 1mm and there are 100 divisions on the circular scale. When nothing is put in between the jaws, the zero of the circular scale lies 8 divisions below the reference line. When a wire is placed between the jaws, the first linear scale division is clearly visible while 72^nd division on circular scale coincides with the reference line, The radius of the wire is:

Consider the following chemical reaction.

$HC\equiv CH\underset{2)CO,HCl,AlC{l}_3}{\overset{1)RedhotFetube,873K}{\to }}Product$            

The number of sp² hybridized carbon atoms (s) present in the product is--------------.

Given below are two statements:

Statement I : α and β forms of sulphur can change reversibly between themselves with slow heating or slow cooling.

Statement II : At room temperature the stable crystalline form of sulphur is monoclinic sulphur.

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 escape velocities of planet Ad and B are same. But A and B are of unequal mass.

Reason R : The product of their mass and radius must be same. M₁ R₁ = M₂R₂

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

Using the provided information in the following paper chromatogram: Fig : Paper chromatography for compounds A and B. The calculated R_f value of A------------* 10^-1

The ionization enthalpy of Na⁺ formation from Na_(g) is 495.8 kJ mol^-1, while the electron gain enthalpy of Br is - 325.0 kJ mol^-1. Given the lattice enthalpy of NaBr is - 728.4 kJ mol^-1. The energy for the formation of NaBr ionic solid is (-) -------------- * 10^-1kJ mol^-1.

A solid sphere of radius R gravitationally attracts a particle placed at 3R form its centre with a force F₁,. Now a spherical cavity of radius $\left(\frac{R}{2}\right)$  is made in the sphere (as shown in figure) and the force becomes F₂. The value of F₁: F₂ is:

The ionization enthalpy of Na⁺ formation from Na_(g) is 495.8 kJ mol^-1, while the electron gain enthalpy of Br is - 325.0 kJ mol^-1. Given the lattice enthalpy of NaBr is - 728.4 kJ mol^-1. The energy for the formation of NaBr ionic solid is (-) -------------- * 10^-1kJ mol^-1.