The number of valence electrons present in the metal among $\mathrm{Cr}, \mathrm{Co}, \mathrm{Fe}$ and Ni which has the lowest enthalpy of atomisation is :

Which of the following is the correct IUPAC name of given organic compound (X)?

At the sea level, the dry air mass percentage composition is given as nitrogen gas: 70.0 , oxygen gas: 27.0 and argon gas: 3.0 . If total pressure is 1.15 atm , then calculate the ratio of following respectively:

(i) partial pressure of nitrogen gas to partial pressure of oxygen gas

(ii) partial pressure of oxygen gas to partial pressure of argon gas

(Given: Molar mass of N, O and Ar are 14, 16 and $40 \mathrm{~g} \mathrm{~mol}^{-1}$ respectively.)

Given below are two statements :

Statement I : Dimethyl ether is completely soluble in water. However, diethyl ether is soluble in water to a very small extent.

Statement II : Sodium metal can be used to dry diethyl ether and not ethyl alcohol.

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