Nutrition: The process by which the living organisms receive and utilise the food materials necessary for their survival, growth and repair of worn-out tissues is called nutrition.
Nutrients: Those substances which supply nourishment to living organisms from its surroundings and use it as an energy source or for biosynthesis of body constituents.

(i) The first group elements have a common valency of 1 and the valency of oxygen is 2 and to satisfy the combining capacity of oxygen, 2 elements of first group are required. Thus the oxide of the first group elements have the common formula of M₂​O.

Ex- Na₂​O,K_2​O,etc.

(ii) The valency of group 13 elements is 1 and the valency of oxygen is 2 and to satisfy the combining capacity of group 13 elements, 3 of halogens are required. Thus the molecular formula will be of form MX₃​.

Ex- AlCl_3​,BF₃​,etc.

(iii) The valency of group 2 elements is 2 and that of group 17 is 1. Thus two elements of group 17 are required to combine with group 2 element.

Ex- MCl₂​,CaCl_2​,etc.

When ferrous sulphate is heated colour changes from light green to reddish brown. On further heating, ferrous sulphate decomposes to form ferric oxide (Fe2O3), sulphur dioxide (SO2) and sulphur trioxide (SO3).

Acceleration due to gravity above the surface of earth

• To calculate the value of acceleration due to gravity of a point mass m at a height h above thesurface of the earth.

Above figure shows the value ofacceleration due to gravity g at a height h above the surface of the earth.

• Force of gravitation between the object and the earth will be

• F= G mM_e/(R_e+h)²  where

• m = mass of the object, R_e = radius of the earth
• g(h) = F/m = GM_e/(R_e+h)² = GM_e/[R_e²(1+h/R_e)²]
• h << R_e (as radius of the earth is very large)

• By calculating we will get,

g(h) = g(1-2h/R_e)

• Conclusion: -The value of acceleration due to gravity varies on the surface, above the surface and below the surface of the earth.

IUPAC name of CH3COOC2H5 is Ethyl acetate / Ethyl ethanoate

The following compound is ester R−COO−R′ and the naming of ester are done on the basis of alkanoate group (R−COO−) and alkyl (R′) combined to form ester.
The suffix for ester is "-oate". The full name of ester is like alkyl alkanoate. 
Thus the name of given compound is ethyl ethanoate.

The frequency of the light ray remains same when it travels from one medium to another because it depends on the source of light. But the wavelength and speed vary because they depend on the medium through which the light passes.

The left half of the heart receives the oxygenated blood from the lungs, It pumps it through the aorta to the body tissues (excluding the lungs). The Deoxygenated blood from the various parts of the body returns to the right half of the heart, via the vena cava. This deoxygenated blood is carried to the lungs for oxygenation through the pulmonary artery. It is then pumped to the heart via the pulmonary vein for circulation to various tissues.

The essential precautions to be taken by using electricity are:
1.Switch off all switches including main switch whenever there is a spark or fire.
2.All connection must be tight. Wires must be covered with proper insulation of proper thickness.
3.Defective switches should be immediately replaced.
4.All electrical appliances should have proper earthing.
5.Whenever repairs are needed switch off the main switch.
6.Fuses of proper rating should always be connected to a live wire.
7.Always put on dry rubber shoes while repairing a circuit.

Two safety measures commonly used in electric circuits and appliances are:

• Electric Fuse: An electric fuse is connected in series it protects the circuit from overloading and prevents it from short-circuiting.

Electric fuse prevents the flow of excessive current through the circuit. When the current passing through the wire exceeds the maximum limit of the fuse element, the fuse melts to stop the flow of current through that circuit, hence protecting the appliances connected to the circuit.

• Proper Earthing of an all-electric circuit in which any leakage of current in an electric appliance is transferred to the ground and people using the appliance do not get the shock.

Earthing is a must to prevent electric shocks. Any leakage of current in an electric appliance is transferred to the ground and people using the appliance do not get the shock.

A reducing agent is one of the reactants of an oxidation-reduction reaction which reduces the other reactant by giving out electrons to the reactant. If the reducing agent does not pass electrons to other substance in a reaction, then the reduction process cannot occur.

Some common reducing agents include metals such as Na, Fe, Zn, Al and non-metals such as C, S, H₂. 

• Plants do not have nervous system or muscles to respond to the stimulus.
• Plants show two different types of movement in respond to the stimulus i) one dependent on growth ii) another independent of growth.

An oxidizing agent (often referred to as an oxidizer or an oxidant) is a chemical species that tends to oxidize other substances, i.e. cause an increase in the oxidation state of the substance by making it lose electrons.

• They are chemical substances whose atoms remove at least one electron from another atom in a chemical reaction.
• An oxidizing agent is a substance that transfers at least one electronegative atom to a chemical species in a chemical reaction.

Common examples of oxidizing agents are listed below

• Halogens (such as chlorine and fluorine)
• Oxygen
• Hydrogen peroxide (H₂O₂)
• Potassium nitrate
• Nitric acid

It is a chemical reaction in which you mix two solutions of two ionic substances and a solid ionic substance (a precipitate) forms.

For example, precipitation occurs when a part of the atmosphere saturates itself with water vapour and when the right temperature comes its condenses and precipitates. The two processes which make the air saturated are the cooling of air molecules and the addition of water vapour.

At sunrise and sunset, the sun is near the horizon. The rays of light from the upper part and lower part of the periphery of the sun bend unequally on travelling through earth's atmosphere. That is why the sun appears oval or flattened at the time of sunrise and sunset.

At noon, the sun is overhead. The rays of light from the sun enter earth's atmosphere normally. Therefore, they suffer no refraction or bending on passing through earth's atmosphere. Hence the sun appears circular at noon.

 Atoms are the smallest particles of an element which can take reaction.

      Size of an atom: Atomic radius is measured in nanometres.

      Atomic radii of hydrogen atom = 1 × 10^–10 m.

      Symbols of atoms:

      (a) Symbols for some elements as proposed by Dalton:

      (b) Symbols of some common elements:

The mineral acid: is inorganic compounds composed of different chemical element combinations. Commonly used mineral acids are sulfuric acid, hydrochloric acid, and nitric acid, etc
 An organic acid is an organic compound essentially composed of carbon and hydrogen atoms.   Now some examples of organic acids are carboxylic acids whose acidity is associated with carboxyl group-COOH, sulphonic acids containing the group-SO₂OH.

<i>Rhizopus</i>, mushroom etc., reproduce by spore formation. The three conditions favourable for spores to germinate and grow are as follows:

• Moisture
• Optimum temperature
• Oxygen 
• Nutrients

Bulb ratting is 100 W and 220 V bulb means when 220 V potential difference is applied between the two ends then power consumed is 100 W
Here V=220 Volt
p=100 W
V²/R=100 

So R=484Ω

v = 36km/hr = 36 × 1000m/ (60×60) s

 = 36 × 1000m/ 3600 s

=10m/s.

Temperature is a measure of the degree of hotness of a body.  The SI unit of temperature is kelvin (K). But temperature is also measured in celcius (°C) or fahrenheit (°F) scales. The instrument used to measure temperature is called a thermometer. 

• The thermometer is washed with water at a normal temperature.
• It is given a few jerks. We notice that the jerks bring the level of mercury down. We make sure that it falls below the 37⁰C mark or the 98⁰F mark, the normal human body temperature.
• The thermometer is then kept under the tongue or under the arms in order to get the reading on the thermometer.
• The thermometer is then held close to the eye as shown in figure 3 in order to see the correct reading.
• The temperature difference indicated between the two bigger marks is noted. Also, the number of divisions (shown by smaller marks) between these marks is noted. For e.g. the bigger mark reads 10 and the number of division is 5, then each division reads the value equal to 10/5 = 20
• We note the value of the bigger mark that the mercury thread has crossed (which is 98 in the Fig.4 Example 1). Then the number of the division of the mercury thread has crossed is noted (3 in this case). Now, this value is multiplied by the value of one division (which is 0.2 in this case). Hence, the temperature reading is 98 + (3×2) = 98.6.

Fuse wire is directly connected in series to the load.It is used to prevent the load from damage in case of excess current.

Earth wire is not exactly in the main circuit .It is connected the body of load to earth It is used to prevent any kind of shock . If there is a current in the body of load due to any fault then this makes a proper path to drop all the current to the earth.

• Joule, unit of work or energy in the International System of Units (SI); it is equal to the work done by a force of one newton acting through one metre.
• Watt is a SI unit of power which is defined as the energy per unit time  
• In simple terms, an electrical conductor is defined as materials that allow electricity to flow through them easily. This property of conductors that allow them to conduct electricity is known as conductivity.
• Myopia, Also Called Near sightedness, is a eye defect in which the patients are not able to see objects at long distances clearly. Persons who are myopic, has their eye lens maximum value decreased. 
• Resistance is a property of conductor due to which it resists the flow of electric current through it.