Diverging lens / concave lens

Focal length = -20 cm (lens is concave, hence f is -ve)
Power = P = 1/f = 100/ -20 cm = -5D.

(i) Vegetable matter changing into compost is exothermic and decomposition reaction.
(ii) Burning of natural gas is exothermic reaction.
(iii) Adding water to quick lime to form slaked lime is combination reaction and exothermic in nature.

Real image is inverted. So, magnification is negative
Thus, m=-3=\(\frac{Image \quad size}{Object \quad size}\)
\(=\frac{h_{i}}{h_{o}}=-\frac{v}{u}\)
[where, v = image distance and u = object distance]
\(\Rightarrow -3=\frac{-(v)}{(-10)}\) [\(\because\) object is placed in front of mirror]
\(\Rightarrow -3=\frac{v}{10}\)
Image distance, v = -30 cm
Negative sign shows that image is real, so it will be formed in front of the mirror.

(i)Bile is helpful in the emulsification of fats i.e., the breaking down of large fat droplets into smaller fat globules, which the pancreatic enzymes can act upon.
(ii)The pancreatic juice contains enzymes that require an alkaline medium to act. The bicarbonate secreted by the duodenum provides this alkaline medium.
(iii)The function of pancreatic amylase is to convert complex carbohydrates into glucose, which is absorbed in the blood.

Carbon based molecules, i.e. food is used by body to meet its energy nced. Oxygen is used to oxidise food which release energy. Water is requircd for operating most of the functions inside the body. So, food, water and oxygen are the basic raw materials used by an organism.

(a) 2KBr(aq) + BaI₂(aq) \(\rightarrow\) 2KI + (aq) + BaBr₂(s)
Type: Double displacement reaction
(b) ZnCO₃(s) \(\overset{\Delta }{\rightarrow}\) ZnO(s)+CO₂(g)
Type: Thermal decomposition reaction
(c) H₂(g)+Cl₂(g)\(\rightarrow\) 2HCl(g)
Type: Combination reaction
(d) Mg(s)+2HCl(aq)\(\rightarrow\)MgCl₂(aq)+H₂(g)
Type: Displacement reaction

In a displacement reaction, a more reactive element displaces a less reactive element from its salt solution. But in a double displacement reaction, two atoms or groups from different compounds displace each other. Chemical equation for single displacement,
 Zn(s) + CuSO₄(aq) \( \longrightarrow \) ZnSO₄(aq) + Cu(s)
Here, Zn displaces Cu from its salt solution (CuSO₄).
Chemical equation for double displacement,
BaCl₂(aq) + K₂SO₄(aq) \( \longrightarrow \) BaSO₄ (s) + 2KCl(aq)
Here, Ba and K displace each other.

(a) This means that the ratio of speed of light in air and the speed of light in diamond
is equal to 2.42
(b) Kerosene

Concave mirror can give erect and enlarged image of an object.

The raw materials for photosynthesis are carbon dioxide and water. These are taken up by the plants in the following ways
(i) CO₂ is taken up through the stomata from the atmosphere in case of land plants, while the aquatic plants take up CO₂ dissolved in water.
(ii) Water is taken up or is absorbed by the roots through the process of osmosis and is transported to the leaves containing photosynthetic cells by the xylem vessels.

(a) Pb(NO₃)₂(aq) + 2KI(aq) \(\rightarrow\) PbI₂(s) + 2KNO₃(aq)
(b) Cu(s) + 2AgNO₃(aq) \(\rightarrow\) Cu(NO₃)₂(aq) + 2Ag(s)
(c) Zn(s) + H₂SO₄(aq) \(\rightarrow\) ZnSO₄(aq) + H₂(g)
(d) CaCO₃(s) \(\overset { Heat }{ \rightarrow } \) CaO(s) + CO₂(g)

(a) (i) 2H₂O\(\overset { electricity }{ \longrightarrow } \) 2H2(g) + O2
(ii) CaCO₃ \(\overset { heat }{ \longrightarrow } \) CaO + CO₂
(iii) 2AgBr \(\overset { sunlight }{ \longrightarrow } \) 2Ag + Br₂
(b) Copper can displace silver from AgN03 because copper is more reactive than Ag
Cu + 2AgNO₃(ag) \(\longrightarrow \) Cu(NO₃)2(aq) + 2Ag(s)

(1) The incident, the refracted ray and the normal at the point of incidence. all lie in the same plane. 
(2) The second law of refraction is called Snell's law of refraction. According to Snell's law. "The ratio of sine of angle of incidence to the sine of angle of refraction is a constant for a given pair of mediums"

\(\frac { sin\ \ i }{ sin \ r } =n(constant)\)
\(\frac { Speed \ of \ light \ in \ vacuum }{ Speed \ of \ light \ in \ medium } =\)
Refractive index of the medium
\(\Rightarrow \frac { 3\times { 10 }^{ 8 }m/s }{ x } =1.5\)
\(\Rightarrow \frac { 3\times { 10 }^{ 8 } }{ 1.5 } =2\times { 10 }^{ 8 }m/s\)
∴ Speed of lightin the medium = 2 x 10⁸ m/s

Photosynthesis is the process by which plant cells prepare food (carbohydrates) from inorganic raw materials such as carbon dioxide and water in presence of sunlight and chlorophyll.
\({ 6CO }_{ 2 }+{ 6H }_{ 2 }O\xrightarrow [ Chlorophyll ]{ Sunlight } { C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+{ 6O }_{ 2 }\)
The process of photosynthesis takes place in two phases:
Light reaction - It requires light which is absorbed by chlorophyll molecules to split water molecules into hydrogen and oxygen. ATP and NADPH₂ are produced during this phase and it occurs in the thylakoid membrane of the chloroplasts.
Dark reaction - It does not require light energy and it occurs in the stroma of chloroplasts, In this phase, the ATP and NADPH₂ formed during light reaction are utilised and CO₂ is reduced to form carbohydrates.
The four factors affecting the rate of photosynthesis are:
(i) Sunlight - Sunlight provides the energy required for the preparation of food by plants. In the absence of sunlight, photosynthesis cannot take place.
(ii) Carbon dioxide - Carbon dioxide acts as the substrate for photosynthesis. During this process, carbon dioxide and water are converted into carbohydrates.
(iii) Water - During photosynthesis, water is photolysed into oxygen and hydrogen and it provides the energy for photosynthesis.
(iv) Chlorophyll - Chlorophyll is the green pigment present in the leaves which absorbs sunlight

(i) The pressure reading was noted at intervals of 5 min and plotted against time of the reaction which involved:
\(\mathrm{CaCO}_3 \xrightarrow{\Delta} \mathrm{CaO}+\mathrm{CO}_2 \uparrow\)
Formation of CO₂ gas increases pressure and is maximum in (0-5) min graph as shown sharp curve in (0-5) min.
(ii) Calcium oxide can be reduced to calcium by heating with sodium metal and calcium oxide acts as an oxidising agent because it oxidises other substance, i.e. sodium and itself gets reduced.
(iii) CO₂ gas is a reactant for a very important biochemical process which occurs in the presence of sunlight, the name of the process is photosynthesis.
The reactants for photosynthesis are light energy, water, carbon dioxide and chlorophyll, while the products are glucose, oxygen and water.
Or
Marble statues are corroded or stained when they repeatedly come in contact with polluted rain water. Polluted rain water is acidic in nature hence, it reacts with calcium carbonate.
CaCO₃(s) + H₂SO₄(aq) \(\rightarrow\) CaSO₄(s) + CO₂(g) + H₂O
The decomposition of calcium carbonate is as follows
\(\mathrm{CaCO}_3(\mathrm{~s}) \xrightarrow{\Delta} \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})\)

(i) (a) W – Sieve plate, Y – Companion cell
The given figure is Lateral Section of phloem in which W represents sieve plate,
X represents sieve tubes,
Y represents companion cell and Z represents phloem parenchyma.
(ii) (a) Sieve tube
Sieve tubes (X) are living cells which contain cytoplasm but no nucleus.
(iii) (d) Either (a) or (b)
The movement of food in phloem can be upward or downward depending on the needs of the plant.
(iv) (d) all of these.
The phloem translocates the food (sugar) made in the leaves. Besides food molecules, phloem also transports amino acids, hormones synthesised in shoot tips and root tips and other metabolites.
(v) (b) Tracheids
Components of phloem are sieve tubes, companion cells, phloem parenchyma and sieve plates. Tracheids are constituent of xylem tissue.

(i) (a): When an object is placed at infinity of convex lens, image will be formed at focus F.
(ii) (b): Virtual and inverted image is formed, when object is placed at focus of the concave lens.
(iii) (c) : When object is placed at focus of a convex lens, highly enlarged or magnified image is formed.
(iv) (b): When an object is placed at distance 2F in front of a convex lens, then the image formed is at a distance 2F on the other of the lens.
(v) (a): Image if formed between focus and optical centre when the object is placed anywhere between optical centre and infinity.