(i) A combination reaction is a reaction in which two or more reactants combine to form a compound.
(ii) It is also called as synthesis reaction (or) composition reaction (a single product).
(iii) S_(s) + O_2(g) → SO_2(g)
(iv) Sulphur reacts with oxygen it produce sulphur dioxide.
(v) Most of combination reactions are exothermic in nature, because they involve the formation of new bonds, which releases a huge amount of energy in the form of heat.

The sun gets its energy through nuclear fusion. In this reaction hydrogen atoms fused to form helium atom. As a result huge energy is radiated on the surface of the sun. This reaction is repeated again and again resulting in the energy output continuously.
\(4 \mathrm{H}^{1} \rightarrow{ }_{2} \mathrm{He}^{4}+2+{ }_{1} e^{0}+\text { energy }\)

Stage is the background appearing when we open the scratch window. The background will most often be white. You can change the background colour as you like.

Plants or animals expressing a modified endogenous gene or a foreign gene is also known as transgenic organism.

Semilunar valves associated with the major arteries leaving the ventricles.

(i) The cancerous cells migrate to distant parts of the body and affect new tissues.
(ii) This process is called metastasis.

(i) The number of water molecule in blue vitriol is five.
(ii) The hot saturated solution of copper sulphate has no water molecule.
(iii) When cooled the hot saturated solutions gain five molecules of water and it will turn to crystal.

There are different types of teeth in rabbit. Hence, called as heterodont denitition.

Glycolysis is the common step in both aerobic and anaerobic pathway.

Becquerel (Bq).

(i) Some detergents having a branched hydrocarbon chain are not fully biodegradable by microorganisms present in water.
(ii) So they settle as insoluble chemical in water bodies.
(iii) To avoid this type of water pollution, we should. use detergents which have straight hydrocarbon chains. 
(iv) Because these are easily degraded by bacteria.

Given: V = 331 ms^-1, λ = 0.20 m, n =?
V = n x λ
331 = n(0.20)
n = \(\frac{331}{0.20}\) = 1655 Hz

(i) One mole (6.023 x 10²³ of entities) of any gas occupies 22.4 litre or 22400 ml at S.T.P.
(ii) This volume is called as molar volume of gas.

(i) Catching a cricket ball the fielder lowers his hands backwards. Because, he stops his hands soon after catching the ball, the ball comes to rest very quickly.
(ii) It means that the momentum of the ball is brought to rest very quickly.
(iii) So the average force acting on the body will be large.
(iv) Due to this large average force, the hands will get hurt.
(v) To avoid getting hurt, the player brings the ball to rest slowly.

(i) Rust is the formation of scaling reddish brown hydrated ferric oxide on the surface of iron containing materials.
(ii) This compound is known as rust and the phenomenon of formation of rust in known as rusting.
(iii) \( 4 \mathrm{Fe}+3 \mathrm{O}_{2}+\mathrm{xH}_{2} \mathrm{O} \rightarrow 2 \mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{xH}_{2} \mathrm{O}\\ \quad \quad \quad \quad \quad\quad\text { (Rust hydrated ferric oxide) } \)