A student using the same two resistors, ammeter, voltmeter and battery, sets up two circuits A and B connecting the two resistors first in series and then in parallel.

If the ammeter and voltmeter readings in the two cases be $I_1,I_2$ and $V_1,V_2$ respectively, he is likely to observe that :

An ammeter has 20 divisions between 0 mark and 2 A mark on its scale. The least count of this ammeter is :

Four students A, B, C and D performed the experiment to determine the focal length of a concave mirror by obtaining the image of a distant tree on a screen. They measured the distances between the screen and the mirror as shown in the diagrams given below :

The correct value for focal length will be obtained by the student :

Assertion: Greater number of individuals are present in lower trophic levels.
Reason: The flow of energy is unidirectional.

Assertion: A geneticist crossed a pea plant having violet flowers with a pea plant with white flowers, he got all violet flowers in first generation.
Reason: White colour gene is not passed on to next generation.

Which of the following is considered as physical and chemical unit of heredity?

Choose the correct answer for the following question. 
Which one is the quadratic equation?
$\frac{5}{x}-3=x^2$
$x\left(x+5\right)=2$
$n-1=2n$
$\frac{1}{x^2}\left(x+2\right)=2$

Find which of the following equations are quadratic:
$7x^3-2x^2+10=(2x-5{)}^2$

Write constant term 
$7x^2-11$

Choose the correct answer for the following question.
Out of the following equations which one is not quadratic equation?
$x^2+4x=11+x^2$
$x^2=4x$
$5x^2=90+5$
$2x-x^2=x^2$