Class 11th

This is a short answer type question as classified in NCERT Exemplar

These are formed by many d-block and/block elements. However, the metals of group 7, 8 and 9 do not form hydride. Unlike saline hydrides, they are almost always non- stoichiometric, being deficient in hydrogen. For example, LaH 2.87, YbH 2.55, TiH 1.5-1.8, ZrH 1.3-1.75. Dihydrogen forms molecular compounds with most of the jp-block elements.

Most familiar examples are CH₄, NH₃, H₂O and HF.

This is a Short Answer Type Questions as classified in NCERT Exemplar
Ans: Here concentration of water cannot be neglected since the solution is very dilute. pH will be less than 7.0. Hence, the total concentration is given as -

  [ H₃O⁺ ] =10^-8+10^-7M.

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: At a given time the reaction quotient Q for the reaction will be given by the expression:

Q= $\frac{\left[\mathbf{H}2\right]\left[\mathbf{I}2\right]}{\left[\mathbf{H}\mathbf{I}\right]\mathrm{}}$  = $\frac{[1*10??*1*10??]}{{\left(2*\mathrm{}10^{-5}\right)}^2}$  = $\frac{1}{2}\mathrm{}$ = 0.25

 = 2.5*10⁻¹

As the value of the reaction quotient is greater than the value of K_c i.e. 1*10⁻⁴ the reaction will proceed in the reverse direction.

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: Correct order of pH is -

NH₄Cl  C₆H₅COONH₄  KNO₃  CH₃COONa

Salts of strong acid and strong base do not hydrolyse and form neutral solution thus, pH will be nearly 7 of KNO₃?  

In sodium acetate, acetic acid remains unionised this results in increase in OH- concentration and pH will be more than 7. 

NH₄Cl formed from weak base,  NH₄OH and strong acid,  HCl, in water dissociates completely, aq. ammonium ions undergo hydrolysis with water to form NH₄OHand H₊ ions resulting in less pH value.

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: Conjugate acid of a weak base is always stronger and conjugate base of weak acid is always strong.

The weak acids are:

⇒H₂O, ROH, CH₃COOH, HCl

⇒HCl > CH₃COOH > ROH > H₂O

⇒ Conjugate base order ⇒ OH⁻>RO⁻>CH₃COO⁻>Cl⁻

This is a short answer type question as classified in NCERT Exemplar

Water-gas shift reaction: The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with steam in the presence of a catalyst to form carbon dioxide and hydrogen.

CO+H₂+H₂O → CO₂+2H₂

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: Higher the value of Kb stronger will be the base. 

K_b-  5.4 * 10^-4 >1.77 * 10^-5 > 1.77 * 10^-9> 1.3 * 10^-14

Decreasing order of basic strength. 

Dimethylamine > Ammonia > Pyridine > Urea

Hence among the given bases, the strongest base is Dimethylamine. 

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: BF₃ does not have a proton but still it acts as a Lewis acid as it is an electron pair acceptor and reacts with NH₃by accepting its lone pair of electrons. The reaction can be represented by Coordinate bond is formed between BF₃ and NH₃. It can be represented as-

  [ BF₃ ← :NH₃]

Nitrogen acts as lone pair donator in this combination

This is a Short Answer Type Questions as classified in NCERT Exemplar

Ans: Conductance of a solution depends upon the number of ions present in the solution since sodium chloride is an ionic compound when mixed in water it ionizes completely forming an aqueous electrolytic solution. Hence, the solution conducts electricity while sugar being a non-electrolyte does not ionize in water and when concentration of NaCl is increased, more Na⁺ and Cl^-  ions will be produced. Hence, conductance increases.