Solution

Pesticides not only bring toxic effect on human and animals but also decrease the fertility of the soil. Some of the pesticides are quite stable and their bio- degradation may take weeks and even months.

SOLUTION

An amphoteric compound is a molecule or ion that can react both as an acid as well as a base. Many metals (such as copper, zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides.

In acid: Al₂O_3?+6HCl ? 2AlCl₃?+3H₂?O

In base: Al₂O_3?+2NaOH+3H₂O ? 2Na[Al(OH)_4?] 

Hence, Al₂?O_3?? is an amphoteric oxide.

Solution

We know that, 

Let x be the mass of solute,

?x=10g

SOLUTION

Lesser the Cationic size, lesser the ionic character. Among Li, Be, Be is small. Among Rb and Mg, Rb is large so that Be forms least ionic mostly covalent and Rb form great ionic bonds.

Thus RbCl and BeCl₂ are the compounds with least and greatest ionic character respectively.

Hofmann developed a method for preparation of primary amines by treating an amide with bromine in a aqueous or ethanolic solution of sodium hydroxide

RCONH₂ + Br₂ + 4NaOH→RNH₂ + Na₂CO₃ + 2NaBr + 2H₂O 

Solution

$$\cfrac { { V }_{ 2 } }{ { T }_{ 2 } } =\cfrac { { V }_{ 1 } }{ { T }_{ 1 } } \Longrightarrow { V }_{ 2 }=\cfrac { 2L\times 299.1 }{ 296.4 } =2.02L$$

Solution

A mixture of acetic acid (a weak acid) and sodium acetate ( its salt with strong base sodium hydroxide) acts as acidic buffer.

Cellulose is a natural linear polymer, a long chain made by the linking of smaller glucose molecules.

Natural rubber is a linear polymer made up of Isoprene (2-Methyl -1, 3 – Butadiene) units.

Solution

$$N_1V_1+N_2V_2+N_3V_3=N_4V_4$$
$$V_4=$$ Final volume $$=1\ L$$
$$5\times N+20\times \dfrac {N}{20}+30\times \dfrac {N}{3}=N_4\times 1000$$
$$\therefore N_4=\dfrac {N}{40}$$