(a) CaOCl₂ (Calcium oxychloride)
(b) CaOCl₂ + CO₂ \(\longrightarrow \) CaCO₃ + Cl₂
   Bleaching    (air)
   powder
(e) Bleaching powder is disinfectant, it can kill germs and hence, it is used in water treatment plant.

Transpiration is important because
(i)it helps in absorption and upward movement of water and minerals from roots to leaves
(ii)it prevents the plant parts from heating up.

Haemoglobin efficiently binds with oxygen and transports it to various parts of the body. Deficiency of haemoglobin is referred to as anaemia. The consequence of such condiion is that the blood is unable to carry sufficient amount of oxygen as required by the body and would cause less respiration.
Also, less energy would be liberated. In anaemia, the person feels weak, skin becomes pale, person feel lethargic and is unable to perform heavy physical tasks.

Saliva is secreted by the salivary glands in the mouth. It contains the enzyme salivary amylase, which breaks down starch into maltose. It lubricates the food before swallowing.

(i) Alkaline medium does not allow milk to turn sour easily.
(ii) When milk is set to curd, the presence of alkali does not allow it to become acidic easily. Hence, this milk take a longer time to set as a curd.

(i) ATP is considered as energy currency of cell. It is used as a fuel in various cellular activities such as contraction of muscles, contractions of nerve impulse, proteins synthesis, etc.
(ii) Stomata and large intercellular spaces present throughout the plant body ensures the sufficient exchange of gases in plant.
(iii) The direction of diffusion mainly depends upon environmental conditions and requirement of plant.

Photosynthesis is a process by which green plants, having chlorophyll, synthesise the simple sugar (glucose) from the simple raw materials, water and carbon dioxide using the energy of sunlight. Oxygen is released in this process.
\(\underset{\begin{array}{c} \text { Carbon } \\ \text { dioxide } \end{array}}{6 \mathrm{CO}_2}+\underset{\text { Water }}{12 \mathrm{H}_2 \mathrm{O}} \xrightarrow[\text { Chlorophyll }]{\text { Sunlight }} \underset{\text { Glucose }}{\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6}+6 \mathrm{H}_2 \mathrm{O}+\underset{\text { Oxygen }}{6 \mathrm{O}_2} \uparrow\)
The photosynthesis takes place in the following three steps
(i) Absorption of light energy by chlorophyll.
(ii) Conversion of light energy into chemical energy and splitting of water molecules into hydrogen and oxygen.
(iii) Reduction of carbon dioxide by hydrogen to form carbohydrate like glucose by utilising the chemical energy.
The steps do not need to take place one after the other immediately. For example, desert plants take up carbon dioxide at night and prepare intermediate which is acted upon by the energy absorbed by the chlorophyll during the day.

(i) Mg + 2HCl\(\rightarrow\)MgCl₂+H₂
Hydrogen gas is produced
(ii) HCl + NaOH\(\rightarrow\) NaCl+H₂O
Neutralisation reaction
(iii) 2HCI(aq)+ CaCO₃(aq)\(\rightarrow\)CaCl₂(aq)+H₂O+CO₂
Calcium chloride is formed.

It is a salt produced by the neutralization reaction between a strong base (NaOH) and a weak acid (H₂CO₃), hence it is a basic salt.
It is heated strongly to produce sodium carbonate
\(2NaCO_3 \xrightarrow{Delta} Na_2CO_3 + H_2O + CO_2\)
Sodium carbonate is recrystallized to produce washing soda
\(Na_2CO_3 + 10H_2O \longrightarrow Na_2CO_3.10H_2O\)

The small intestine is the main region for the absorption of digested food. The inner lining of the small intestine is covered by millions of tiny finger-like projections called villi. The presence of villi gives the inner walls of the small intestine a very large surface area for the absorption of digestad food.

Structure of nephron Nephron is the basic filtering unit found in kidney. It is a long coiled tubule whose one end is connected to the double walled cup-shaped structure called Bowman's capsule and the other end to a urine collecting duct. Bowiman's capsule contains a bundle of blood capillaries, known as glomerulus that is followed by the tubular part of nephron, which forms loops at some places. For figure refer to "Structure of a nephron" on.
Functioning of nephron
(i) Glomerulus filters the blood passing through it.
(ii) It also ensures to remove only harmful substances from the body that includes nitrogenous materials.
(iii) The useful substances like glucose, amino acids, salts and a major amount of water are selectively reabsorbed by the tubular part of nephron.
(iv) Some substances like K⁺ are actively secreted into the urine through the tubule.
(v) The collecting duct collects the urine and passes it to the ureter.

(i) Tap water contains ions which conduct electricity, distilled water does not contain ions.
(ii) Dry HCI does not form ions but dilute HCI gives H⁺ and Cl^- ions in solution.
(iii) Baking soda does not allow milk to change to lactic acid which makes milk sour.
(iv) Adding water to acid is highly exothermic. Therefore, water is added to acid very slowly with cooling.
(v) Ammonia dissolves in water and accept H⁺ from H₂O molecules to release OH^- ions in solution. Therefore, it is basic in nature.

(a) 'X' is CaCO₃ (calcium carbonate). The gas evolved is CO₂.
                          CaCO₃ + H₂SO₄ (dil.) \(\longrightarrow \) CaSO₄ + H₂O + CO₂
                                                           Calcium sulphate
(b) (i) NaHCO₃ is antacid. It neutralizes excess of acid formed in the stomach.
(ii) The soil is acidic in nature. The farmer wants to make it neutral by adding quicklime which neutralise the acid in the soil.