What causes Brownian movement in a colloidal solution?

1

(a)

It is due to unbalanced collision between colloidal particles and with the particles of dispersion medium.

Which is a stronger reducing agent, SbH₃ or BiH₃, and why?

1

(a)

As we move down the group 15 elements from Sb to Bi, the atomic size increase and hence the strength of the bond it makes with hydrogen decreases, i.e., Bi-H bond is weaker than Sb-H bond.  In other words, BiH₃ is thermally less stable than sbH₃.  Therefore, on heating, BiH₃ has a greater tendency to liberate hydrogen than SbH₃ is a stronger reducing agent than SbH₃.

Write balanced chemical equation for the reaction : phosphorus is treated with concentrated nitric acid.

1

(a)

Orthophosphoric acid is produced
\(P_4\ +\ 20\ HNO_3\ \rightarrow\ \underset {Orthophosphoric\ acid} {4\ H_3PO_4} +\ 20\ NO_2\ +\ 4\ H_2O\)

                       \(\)

Write one chemical reaction to show that conc.  H₂SO₄ can act as an oxidising agent.

1

(a)

Hot concentrated sulphuric acid oxidises carbon to CO_2.
\(C + 2\ H_2SO_4(conc.)\overset{\triangle}{\longrightarrow} CO_2+2\ SO_2+2\ H_2O\)

                    \(\)

Why does a transition series contain 10 elements ?

1

(a)

There are five d - orbitals in an energy level and each orbital can have two electrons. As we move from one element to the next, an electron is added and for complete filling of the ive d orbitals, 10 electrons are required.

Explain why lanthanoids are paramagnetic in nature ?

1

(a)

All lanthanoids expect La³⁺ and Lu³⁺ contain unpaired electrons and hence are paramagnetic.

Write the chemical formula of nitropentaamminecobalt (III) chloride.

1

(a)

\([Co\ (NH_3)_5(NO_2)]\ CI_2\)

What is the oxidation state of Ni in Ni(CO)₄ ?

1

(a)

Zero

What is the condition to be satisfied for a compound to be chiral?

1

(a)

Its mirror image should be non-superimposable.

What is the order of reactivity of HCl, HBr and Hl with alcohols?

1

(a)

Reactivity decreases as the strength of the H--X bond increases,i.e,Hl  >  HBr  >  HCl

What is 'Power alcohol'?

1

(a)

A mixture of absolute alcohol (20%),petrol (80%) and some benzene as a cosolvent is called power alcohol.

What is invert sugar ? 

1

(a)

An equimolar mixture of glucose and dructose, obtained by hydrolysus of surcose in pressure of an acid such as dil. HCI or the enzyme invertase, is surcrase, is called invert sugar.

What causes the disease sickle cell anaemia ?

1

(a)

Defective haemoglobin which is produced due to replacement of one amino acid, i.e., glutamic acid by valine.

What is a Gene?

1

(a)

The segment of DNA molecule which codes for a specific protein or polypeptide is called a gene.

Which site of an enzyme is called allosteric site? 

1

(a)

Sites different from active site of enzymes where a molecule can bind and affect the active site is called allosteric site.