Predict what happens to entropy in the following changes:
a) Metal is converted into alloy.
b) Solute crystallizes from solution.
c) Hydrogen molecule dissociates.

a) Predict whether entropy increases or decreases in the following changes: i) l_2(S)rightarrowl_2(g) ii) Temperature of a crystalline solid is raised from 0 K and 115 K. iii) Freezing of water b) Calculate the enthalpy of combustion of methane. Given that standard enthalpies of formation of CH_4,CO_2 and H_2O are -75.2, -394 and -285.6 kJ/mol respectively.

Predict the entropy change (positive/negative) in the following: i) A liquid substance crystallizes into a solid. ii) Temperature of a crystal is increased. iii) 'CaCO_3(s) rarr CaO(s) rarr O_2(g)' iv) 'N_2(g)(1 atm) rarr N_2(g)(0.5 atm)'

Ammonia is a base because it has a lone pair of electrons. Predict the change in -basicity in the following cases and give reason for each. a) When one hydrogen of ammonia is replaced by methyl group. b) When one hydrogen of ammonia is replaced by phenyl group.

A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution? a)The solution is non-ideal, showing negative deviation from Raoult's Law b)The solution is non-ideal, showing positive deviation from Raoult's Law c)n-heptane shows positive deviation while ethanol shows negative deviation from Raoult's Law d)The solution formed is an ideal solution

State whether the following sentences are true or false: (a) Metals in the second group are called alkali metals. (b) Alkali metals are not found in free state in nature. (c) Baking soda is chemically sodium hydrogen carbonate. (d) Portland cement is basically silicates and alu minates of calcium.

What happens when the following process take place? Give chemical equation for the process:- When acidified KMnO_4 added to FeSO_4 solution.

What happens when the following process take place? Give chemical equation for the process:- When H_2S is passed through acidified potassium dichromate solution.

State whether the following statements are true or false. a. In benzene, carbon uses all the three p obitals for hybridisation. b. Ácetylene is a tetrahedral molecule. c. Branched chain alkanes, alkenes and aromatic hydrocarbons have high octane numbers. d. Ethyne can be distinguished from ethene by using cold dilute KMnO_4^- e. In cracking, the larger molecule are broken down into smaller molecules and in reforming, cyclic and acyclic alkanes are converted into arenes.