Questions

The stability of the ions is determined by the energy of the lone pairs. Carbon has the least effective nuclear charge (Zeff) and so the lone pair on the CH3− ion has the highest energy, making it the least stable ion and so the strongest base. The Zeff increases as we move across the period until we get to fluorine which has the greatest Zeff and so its lone pairs have the lowest energy, making F− the least basic ion.

In order of decreasing basicity they are ranked LiCH3 > LiNH2 > LiOH > LiF. We are dealing with the ions F−, OH−, NH2− and CH3− and so the factor which influences their basicity is the stability of the ion compared to its conjugate acid.

Here Homologous Means having the same relation or relative position or structure. 

Here in snakes poison is in glands and here salivary glands are in Vertebrates.

Probability of sending the correct material is 4/5

Probability of the material not being damaged in transit is 1/4

Probability that there is no short shipment = 2/3

∴ Required probability =4/5 x 1/4 x 2/3 = 2/15

Subhash C. Garg, a 1983 batch lAS officer of Rajasthan cadre, has been appointed as the new the economic affairs secretary in the Union Finance Ministry. The post fell vacant after Shaktikanta Das retired on May 31, 2017. Currently, Tapan Ray, the corporate affairs secretary, has the additional charge of the economic affairs department. Prior to this appointment, Garg was Executive Director at World Bank for Bangladesh, Bhutan, India and Sri Lanka.