i) Mitochondria is the power house of cells.
ii) Because produces a large number of ATP molecules.

The process in which two lighter nuclei combine to form a heavier nucleus is termed as "nuclear fusion".
Eg: ₁H² + ₁H²- ₂He⁴ + Q (Energy)
Here, ₁H² represents an isotope of hydrogen known as "deuterium". The average energy released in each fusion reaction is about 3.84 x 10^-12J.

The elements whose atomic number is more than 83 undergo spontaneous radioactivity.
Ex : Uranium, Radium, etc.
Technetium (Tc) with atomic number 43 and Promethium (Pm) with atomic number 61 are the only tow radio active substances.

Avogadro's law states that "equal volumes of all gases under similar conditions of temperature and pressure contain the equal number of molecules"

There are eleven pairs of testes in leech.

The Indian cattle leech.

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

Atomic number -106 ; Mass number - 263 (In alpha decay atomic number decrease by two and mass number decrease by four)

The total number of atoms present in the molecule is called its atomicity.
\(\text { Atomicity }=\frac{\text { Molecular mass }}{\text { Atomic mass }}\)

Male Reproductive system
(i) Male reproductive system of rabbit consists of a pair of testes which are ovoid in shape.
(ii) Testes are enclosed by scrotal sacs in the abdominal cavity
(iii) Each testis consists of numerous fine tubules called seminiferous tubules
(iv) This network of tubules lead into a coiled tubule called epididymis, which lead into the sperm duct called vas deferens.
(v) Below the urinary bladder is the urethra. Vas deferens joins the urethra.
(vi) Urethra runs backward and passes into the penis.
(vii) There are three accessory glands namely prostate gland, cowper's gland and perineal gland. Their secretions are involved in reproduction.

a) Monocot root and dicot root

b) Aerobic respiration and anaerobic Respiration:

A Nuclear reactor is a device in which the nuclear fission reaction takes place in a self-sustained and controlled manner to produce electricity.
(i) Fuel:
a) A fissile material is used as fuel.
b) The commonly used fuel material is uranium
(ii) Moderator:
a) A moderator is used to slow down the high-energy neutrons to get slow neutrons.
b) Graphite and heavy water are the commonly used moderators.
(iii) Control rod:
a) Control rods are used to control the number of neutrons in order to have a sustained chain reaction.
b) Mostly boron or cadmium rods are used as control rods.
(iv) Coolant:
a)A coolant is used to remove the heat produced in the reactor core to produce steam.
b) This steam is used to run a turbine to produce electricity.
c) Water, air and helium are some of the coolants.
(v) Protection wall:
 A thick concrete lead wall is built around the nuclear reactor in order to prevent the harmful radiations from escaping into the environment.

(a) Controlled chain reaction:
(i) In the controlled chain reaction the number of neutrons released is maintained to be one.
(ii) This is achieved by absorbing the extra neutrons with a neutron absorber leaving only one neutron to produce further fission.
(iii) Thus, the reaction is sustained in a controlled manner.
(iv) The energy released due to controlled chain reaction can be utilized for constructive purpose.
(v) Controlled chain reaction is used in a nuclear reactor to produce energy in a sustained and controlled manner.
(b) Uncontrolled chain reaction:
(i) In the uncontrolled chain reaction the number of neutrons multiplies indefinitely and cause fission in a large amount of fissile material.
(ii) This results in the release of huge amount of energy within a fraction of second.
(iii) This kind of chain reaction is used in atom bomb to produce explosion.

(i) An atom is no longer indivisible.
(ii) Atoms of the same element may have different atomic masses (isotopes ₁₇Cl³⁵, ₁₇Cl³⁷)
(iii) Atoms of different elements may have the same atomic masses (isobars ₁₈Ar⁴⁰, ₁₇Ca⁴⁰)
(iv) Atoms of one element can be transmuted into atoms of other elements. So atom is no longer indestructible. It is called artificial transmutation.
(v) Atoms may not always combine in a simple whole number ratio [Eg: Glucose C₆H₁₂O₆, sucrose C₁₂H₂₂O₁₁)
(vi) Atom is the smallest particle that takes part in a chemical reaction.
(vii) The mass of an atom can be converted into energy (E = mc²).

(i) 27 g of AI
Number of moles = \(\frac{Given\ Mass}{Atomic \ Mass}=\frac{27}{27}=1\)
Number of moles of 27 g of Al is 1 mole
(ii) 1.51 x 10²³ molecules of NH₄Cl
Number of moles = \(\frac{Number \ of \ molecules}{6.023 \times 10^\text{23}}\)
= \(\frac{1.51 \times10^{23}}{6.023 \times10^{23}}\) 
\(\frac{1.51}{6.023}\)
Number of moles of 1.51 x 10²³ molecules of NH₄Cl = 0.25 mole

Leech is a parasite and sucks the blood of vertebrates and show adaptations.
(i) Suckers are present in the anterior and posterior ends of the body, by which the animal attaches itself to the body of the host.
(ii) The three jaws inside the mouth causes a triradiate or Y shaped wound in the skin of the host.
(iii) Saliva contains a protein called hirudin which prevents the blood clotting. Thus continuous supply of blood is maintained.
(iv) Blood is stored in the crop. It gives nourishment to the leech for several months. Hence, there is no digestive juices and enzyme.

Rings of cartilages are found in the tracheal walls of rabbit to help in the free passage of air.

(i) ₁₃AI²⁷ + ₂He⁴  \(\longrightarrow \) ₁₅P³⁰ + ₀n¹
(ii) ₁₂Mg²⁴ + ₀n¹  \(\longrightarrow \) ₁₁Na²⁴ + ₁H¹
(iii) ₉₂U²³⁸ + ₀n¹ \(\longrightarrow \) ₉₃Np²³⁹ + _-1e⁰
A is alpha particle, B is neutron, C is proton, and D is electron.

Carbon dioxide + Water ➝ Glucose + Water + Oxygen

(i) Radiation emitted by the X-ray machine can easily passes through our body and can cause genetic diseases.
(ii) These have been passed by genetic diseases from generation to generation. 
(iii) When the emitted radiation is so high, it leads to death. So Mr. Ramu must wear the lead aprons.

Soddy and Fagan's displacement laws:
(i) When a parent element emits an alpha particle the new element is formed with a decrease in atomic number by two and mass number by four.
(ii) When a parent nucleus emits a beta particle the daughter nucleus is formed with an increase in atomic number by one and has same mass number of the parent nucleus.
(iii) In gamma decay, the energy level of nucleus only changes. No new elements are formed.

molecular mass of H₂SO₄
= (1 × 2) + (32 × 1) + (16 × 4)
= 2 + 32 + 64
= 98 g
% of S in H₂SO₄ = \(\frac { Mass\ of\ sulphur }{ Moleculer\ mass\ of\ H_2\ SO_4 } \times 100\)
% of S in H₂SO₄ = \(\cfrac { 32 }{ 98 } \times 100\)
= 32.65%

\(\text { Molar mass of } \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}=\mathrm{Al} \times 2+3[\mathrm{~S} \times 1+\mathrm{O} \times 4]\)
\(27 \times 2+3[32 \times 1+16 \times 4]\)
= 54 + 3[32 + 64]
= 54 + 3 [96]
Molar Mass = 54 + 288 = 342
\(\text { Mass } \% \text { of an element }=\frac{\text { mass of that element in the compound }}{\text { molar mass of the compound }} \times100\)
\(\text { Mass } \% \text { oxygen in } \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}=\frac{192}{342} \times 100 \)
\(=0.5614 \times 100=56.14 \% \)
\(\text { Mass } \% \text { of oxygen in } \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3} \text { is } 56.14 \%\)