(I) CuO(s) + H₂(g) \(\rightarrow \) Cu(s) + H₂O(g)
(ii) Redox reaction.

\(CaSO_4.{1\over 2}H_2O\)(Calcium sulphate hemihydrate)
When plaster of paris reacts with water
\(\underset{Plaster\ of\ Paris}{CaSO_4.{1\over 2}H_2O}+1{1\over 2}H_2O\longrightarrow\underset{Gypsum} {CaSO_4.2H_2O}\)

Given, Potential difference, V = 220 V
Power, P = 10 W; Current, I = 5 A
\(\therefore\) Resistance of bulb,
\(R'=\frac{V^{2}}{P}=\frac{220\times 220}{10}=4840 \Omega \)
Since, bulbs are connected in parallel,
Equivalent resistance (R)
\(=\frac{Individual \quad resistance (R')}{Number \quad of \quad bulbs \quad (n)}\)
\(\Rightarrow R=\frac{4840}{n}\Omega, V=IR \)
\(\Rightarrow 220=\frac{5\times 4840}{n}\)
\(\Rightarrow n=\frac{5\times 4840}{220}=110 \quad bulbs\)

(i) Rainwater harvesting-it means rain water should not be allowed flow into the drains but make it percolate into the soil more efficiently.
(ii) Recycling of water used in bathrooms and kitchens should be encouraged.
(iii) Construction of dams.

(i) Water harvesting means capturing rainwater where it falls or capturing the run off in a local for future use.
(ii) Two water harvesting structures are Khadins in Rajasthan and Kulchas in Himachal Pradesh.

(i) When sunlight enters the earth's atmosphere, the atoms and molecules of different gases in the atmosphere absorb this light and re-emit light in all directions. This process is known as scattering of light. When sunlight passes through the atmosphere having the molecules of air and other fine particles, whose size is smaller than the wavelength of visible light, these molecules and particles scatter the blue colour more strongly than the other colours of spectrum as the wavelength of blue light enters our eye. So, the colour of sky appears blue to us during day time.
(ii) The sun and the surrounding appear red at sunrise and at sunset. This is because, at the time of sunrise and sunset, the sun is near the horizon and so the sun has to travel greatest distance through the atmosphere to reach us. During this travel, most of the shorter wavelength present in it are scattered out from our sight and only the longer wavelength i.e., red colours is left out which makes the sun appears red.

Stop wastage of water.
(a)Switching off unnecessary lights and fans
(b)Reuse carry bags, packing materials,plastic containers and other reusable materials.
(c)Walking down or use cycle for going to nearby market instead of using vehicle.

A male has one X chromosome and One Y chromosome. Thus half the sperms will have X chromosomes and the other half will have Y chromosome. A female has two X chromosomes. So all the female gametes will have only X chromosomes. If a sperm carrying X chromosome fertilizes an ovum then the child born will be a girl. If a sperm carrying Y chromosome fertilizes an ovum then the child born will be a boy.
Thus the chromosomal difference between sperms and eggs of humans determines the sex of the child.

(1) Tendency to lose electrons decreases from left to right across a period.
(2) tendency to lose electrons increases from top to bottom in a group.

(a) It belongs to the 4th period because it has four energy shells and period number of an element is equal to the number of energy shells.
(b) It belongs to 2^nd group because it has 2 valence electrons and the group number of an element having up to two valence electrons is equal to the number of valence electrons.
Its valency is '2'. To acquire inert gas configuration 'X' either loses 2 electrons or gains 6 electrons. Since the shorter route is to lose 2 electrons for obtaining inert gas configuration, hence its valency is 2.

(i) Ethanol gets oxidised to ethanoic acid.
\(\underset{Ethanol}{CH_3CH_2OH}+2[O]\xrightarrow{Alkaline\ KMnO_4}\underset{Ethanoic\ acid}{CH_3COOH}+H_2O\)
(ii)Ethene will be formed
\(\underset{Ethanol}{CH_3CH_2OH}\xrightarrow[443K]{conc. H_2SO_4}\underset{Ethane}{CH_2=CH_2}+{H_2O}\)
Uses:
(i) It is used in tonics and cough syrups.
(ii) It is used as fuel.
(iii) It is used as solvent
(iv) It is used in wine, beer and whisky

(a) There are three possible structural formulae of ester with molecular formula C₄H₈O₂·
\(CH_3CH_2COOCH_3, HCOOCH{_2},CH_3COOC_2H_5\)
(b)\(\underset{Methyl\ propanote\\ (C_4H_8O_2)}{CH_3CH_2COOCH_3}+NaOH\rightarrow \underset{Sodium\ propanoate}{CH_3CH_2COONa}+\underset{Methane}{CH_3OH}\)
(c)\(\underset{Methyl\ methanoate\\\ (C_4H_8O_2)}{CH_3COOC_2H_5}+NaOH\rightarrow\underset{Sodium\ methanoate}{CH_3COONa}+\underset{Propanol}{C_2H_5OH}\)

The major events during photosynthesis are
(i)absorption of light energy by chlorophyll
(ii)Conversion of light energy to chemical energy
(iii)splitinh of H₂,O₂ and e^-
(iv)reducing of CO₂ to carbohydrates

It is easier to obtain metal from its oxide, as compared from its sulphides and carbonates.

Tropic Movement : It is the movement of plants towards stimulus.
Example - stem growth, root growth, pollen tube growth etc.
nastic Movement : Which the movement of plant is neither towards nor away from the stimulus, it is called nastic movement.
Example : Movement in the leaves of touch me not plants in which leaves fold when touched

(a) Pineal Gland
(b) Pancreas
(c) Adrenal gland
(d) Testis

The metallic oxides which show the properties of acids as well as bases are called amphoteric oxides. It means that they react with both bases and acids to form salt and water.
e.g. ZnO and Al₂O₃
ZnO(s)                         +   2HCl(aq)            \(\rightarrow\) ZnCl₂ (aq)    + H₂O(l)
Zinc oxide (As a base) Hydrochloric acid      Zinc chloride    Water
ZnO(s)                         + 2NaOH(aq)            \(\rightarrow\) Na₂ZnO₂(aq) + H₂O(l)
Zinc oxide (As an acid)  Sodium hydroxide      Sodium zincare   Water

Iron reacts with HCl to release hydrogen gas and iron chloride is formed. This reaction is called as displacement reaction.

\(\underset{Potassium\ chloride}{KCl(aq)}+\underset{Silver\ nitrate}{AgNO_3(aq)}\rightarrow\underset{Silver\ chlorie\\ (white\ ppt)}{AgCl(s)\downarrow}+\underset{Pottassium\ nitrate}{KNO_3(aq)}\)
The is Precipitation as well as double displacement reaction.

The conduction of electricity in the two cases is different.  Metals conduct electricity due to the mobile electrons present on their surfaces whereas ionic compounds conduct electricity due to the movement of ions either in molten state or in aqueous solution.  Ionic solids do not conduct electricity because ions do not move in solid state.

(a) 2HNO₃   +   Ca(OH)₂            \(\rightarrow\) Ca(NO₃)₂          + 2H₂O
Nitric acid      Calcium hydroxide     Calcium nitrate     Water
(b) 2NaOH          + H₂SO₄             \(\rightarrow\) Na₂SO₄           +    2H₂O
Sodium hydroxide  Sulphuric acid     Sodium sulphate   Water
(c) NaCl            +    AgNO₃         \(\rightarrow\)  AgCl            +  NaNO₃
Sodium chloride    Silver nitrate      Silver chloride    Sodium nitrate
(d) BaCl₂          + H₂SO₄             \(\rightarrow\) BaSO₄              + 2HCl
Barium chloride    Sulphuric acid     Barium sulphate   Hydrochloric acid

Magnesium ribbon reacts with oxygen present in air to form a protective and inert layer of magnesium oxide on its surface. This layer is unreactive and prevents the ribbon from burning. Hence, it needs to be cleaned with sand paper before burning in air.

The different criteria that can be used to decide whether something is alive are the various features of living organisms, which are as follows
Movement, growth, metabolism, nutrition, respiration, transportation, excretion, response to stimuli, etc