Difference between mass and weight:

Plants and Animals differ as given in the table below:

(i) This is because solid carbon dioxide on decreasing pressure gets converted into gaseous carbon dioxide.
(ii) The water from the ground gets evaporated taking the latent heat of vaporisation from the ground and surrounding air which then becomes cool.

These are:
(i) Catla fish is surface feeder.
(ii) Rohu fish feed in the middle zone of the pond i.e., they are column feeders.
(iii) Mrigal and common carp fishes feed on at the bottom of the pond.
(iv) Grass carps feed on aquatic weeds in the pond.

Mass of bullet, \(m_1=50 \ g = 0.05 kg\)
Mass of rifle,   \(m_2=4\) kg
Initial velocity of bullet, \(u_1=0\)
Initial velocity of rifle, \(u_2=0\)
Final velocity of bullet, \(v_1=35 ms^{-1}\)
Final velocity of rifle, \(v_2 = ?\)
According to the law of conservation of momentum,
total momenta after the fire = Total momenta before the fire
 \(m_1v_1+m_2v_2=m_1u_1+m_2u_2\)
 \(0.05 \times 35 + 4v_2=0+0\)
\({ v }_{ 2 }=-\frac { 0.05\times 35 }{ 4 } =-\frac { 7 }{ 16 } =-0.44{ ms }^{ -1 }\)
The negative sign indicates that the direction in which the rifle would recoil is opposite to that of the bullet.    

23 gram atomic unit or 23 gram sodium (1 mole) = 6.022 x 10²³ atoms
100 gram atomic unit or 100 gram sodium (1 mole) = \(\frac { 6.022\times { 10 }^{ 23 }\times 100 }{ 23 } =2.617\times { 10 }^{ 24 }\)atoms
again 56 gram atomic unit or 56 grams iron (1 mole) =  6.022 x 10²³ atoms
100 gram atomic unit or 100 grams iron = 1.075 x 10²³ atoms
Thus 100 g of carbon has more atoms than 100g of iron.

Solutions.When two reacting substances are kept in contact, the reaction does not take place or is very slow. But when their solutions are mixed, the reaction takes place very fast. This happens because in solutions, reacting substances come in contact with each other at molecular level. When solid washing soda is poured over cloths, it does not wash but when clothes are mixed with solution of washing soda, clothes are easily cleaned.
Colloids Some insoluble substances particularly in pharmaceuticals become effective when administered in colloidal form. many medicines are insoluble in water but are used in the form of colloids.
Suspensions. Many substances insoluble or sparingly soluble in dispersing medium become useful for analytical purpose when dispersed temporarily. For example, sparingly soluble barium sulphate dispersed in water is an opaque medium and is used for diagnostic X-rays.

(i) Worms that affect stomach and intestines
(ii) Fluckes damage the liver.

(a) Energy is defined as the capability to do work.
(b) When an object does work, it loses energy.
(c) When work is done on an object, the object gains energy.
(d) One joule of energy is the energy required to do 1 joule of work.

As the weight of body is a force acting vertically downwards towards the centre of the earth, it has both magnitude and direction. Therefore, weight is a vector quantity.

As the weight of a body is the force with which it is attracted towards the centre of the earth, the SI unit of weight is same as that of force, i.e., Newton (N)

Let the masses of the two blocks be \(m_1\) and \(m_2\)  respectively, and a and 5a be their respective accelerations.
For first block   \(F_1=m_1.a\)
For second block    \(F_2=m_2.5a\)
\(\because\)   \(F_1=F_2\)
\(\therefore\)    \({ m }_{ 1 }a={ m }_{ 2 }.5a\)  or    \(\frac { { m }_{ 1 } }{ { m }_{ 2 } } =\frac { 5 }{ 1 } =5:1.\)

(i) Yes, a body can have acceleration even when it has a uniform speed. A body in uniform circular motion has uniform speed but at every point its direction of velocity changes, so its motion is accelerated.
(ii) Yes, a body can have acceleration even when its velocity is zero. When a body is thrown up, at the highest point it's zero but it has acceleration equal to the acceleration due to gravity.

(a) It would have contributed in disturbing the ecological balance of the pond/lake or any such water bodies.
(b) He is environment friendly because he is conserving biodiversity and not destroying species unnecessarily.
(c) By spreading awareness in the community members about the importance of diversity, by developing empathy and love for all living organisms.

(i) Percentage of oxygen = \(\frac { 0.144 }{ 0.24 } \times 100\) = 60
Percentage of boron = \(\frac { 0.096 }{ 0.24 } \times 100\)= 40
(ii) 16 g oxygen = 1 mole
0.144 g oxygen = \(\frac { 0.144 }{ 16 } \) = 0.009 mole

Every liquid has a characteristic boiling point at 1 atmospheric pressure. If the given colourless liquid boils at exactly 373K at 1 atmospheric pressure, then it is pure water if the boiling point is even slightly above 373K, then contaminated.

Height of object A,\({ h }_{ 1 }=\cfrac { 1 }{ 2 } g{ t }_{ 1 }^{ 2 }\)
Height of object B,\({ h }_{ 2 }=\cfrac { 1 }{ 2 } g{ t }_{ 2 }^{ 2 }\)
\(\therefore \) \({ h }_{ 1 }{ h }_{ 2 }={ t }_{ 1 }^{ 2 }:{ t }_{ 2 }^{ 2 }\)
or  \({ t }_{ 1 }:{ { t }_{ 2 }=\sqrt { { h }_{ 1 } } :\sqrt { { h }_{ 2 } } }\)
(i) Acceleration due to gravity is independent of mass of falling body. So, ratio remains the same
(ii) If bodies are hollow, then also ratio remains the  same, i.e.\({ t }_{ 1 }:{ { t }_{ 2 }=\sqrt { { h }_{ 1 } } :\sqrt { { h }_{ 2 } } }\)
 

(t) Let the two bodies have masses m) and mz and they are placed at the same distance R from the centre of the earth. According to the question, if the sameforce  acts on both of them, then
\({ F }_{ 1 }=\cfrac { GM{ m }_{ 1 } }{ { R }^{ 2 } } \)
and \({ F }_{ 2 }=\cfrac { GM{ m }_{ 2 } }{ { R }^{ 2 } } \)
As, F₁=F₂
Hence,\(\cfrac { GM{ m }_{ 1 } }{ { R }^{ 2 } } =\cfrac { GM{ m }_{ 2 } }{ { R }^{ 2 } } \)
So, m₁ = m₂, their masses will be same
(ii) Mathematically,\(g=\cfrac { GM }{ { R }^{ 2 } } \)
where, g= acceleration due to gravity
G = universal gravitational constant
M = mass of the earth
and R = radius of the earth 
(ii) G is known as the universal gravitational constant because its value remains same all the time everywhere in the universe, applicable to all bodies whether celestial or terrestrial.