1. Fishes are poikilothermic, aquatic vertebrate with jaw.
2. Body is streamlined and differentiated into head, trunk, and tail.
3. Locomotion is by paired and median fins.
4. Body has covering of scales.
5. Respiration is performed by gills. Gill slits are 5-7 pairs.

Rf value is defined as the ratio of the distance travelled by the solute spots to the distance travelled by the solvent
 Rf = \(\frac { Distance\ travelled\ by\ the\ solute }{ Distance\ travelled\ by\ the\ solvent } \)

Total distance travelled by the object = 16 m + 16 m = 32m
Total time taken = 4s + 2s = 6s
Average speed \(=\frac { Total\ distance\ travelled }{ total\ time\ taken } =\frac { 32m }{ 6s } =\frac { 32 }{ 6 } =5.33m{ s }^{ -1 }\)
Therefore, the average speed of the object is 5.33ms^-1

1. Concave mirror
2. Concave mirror.

1. Laws of conservation of mass:
In a chemical change the total mass of the reactant is equal to the total mass of the products.
2. Law of definite proportion:
"A pure chemical compound prepared by any method consists of the same elements combined together in the fixed proportion by mass".
3. Law of multiple proportion: 
When two elements A and B combine together to form more than one compound, then masses of A which separately combines with a fixed mass of B are in simple ratio.
4. Laws of Reciprocal proportion:
"If two elements combine separately the same weight of a third element, the ratios of the masses in which they do so are either the same or a simple multiple of the mass ratio in which they combine.
5. Gay Lussac's law of combining volumes:
Whenever gases react together, the volumes of the reacting gases as well as the products bear a simple whole number ratio, provided all the volumes are measured under similar conditions of temperature and pressure.

Glucose.

Certain soilds change directly to gas without passing through the liquid state. The direct change of a solid to gas is called sublimation.
Example: dry ice, naphthalene, iodine.

A standard unit is defined as a specific magnitude of a physical quantity that has been adopted by law or convention.

Graph shows the change in velocity with time for an uniformly accelerated object. The object starts from the point 'D' in the graph with velocity 'u'. lts velocity keeps increasing and after time 't' it reaches the point 'B'.on the graph.
The initial velocity of the object = u = OD = EA.
The final velocity of the object = v = OC = EB
Time = t = OE = DA
Also from the graph we know that, AB = DC
First equation of motion:
By definition, acceleration = change in velocity / time
= (final velocity - initial velocity)/ time
= (OC - OD) / OE
= DC / OE
a =DC / t
DC = AB = at
From the graph EB = EA + AB
v = u + at ... (1)
This is first equation of motion.
Second equation of motion:
From the graph the distance covered by the object during time t is given by the area of quadrangle DOEB.
s = area of the quadrangle DOEB
= area of the rectangle DOEA + area of the triangle DAB
= (AE x OE) + (1/2 x AB x DA)
s = ut + 1/2 at² ... (2)
This is second equation of motion.
Third equation of motion:
From the graph the distance covered by the object during time t is given by the area of the quadrangle DOEB. Here DOEB is a trapezium. Then
S = area of trapezium DOEB
= 1/2 x sum of length of parallel side x distance between parallel sides
= 1/2 x (OD + BE) x OE
S = 1/2 x (u + v) x t
since a = (v - u) / t or t = (v - u) / a.
Therefore s = 1/2 x (v + u) x (v - u) / a
2as = v² - u²
v² = u² + 2 as     ......(3)
This is third equation of motion.