CBSE 11TH PHYSICS - Online Test

Answer : Option D
Explaination / Solution:

Axial vector represent rotational effect and are always along the axis of rotation. Direction of angular momentum always along the axis of rotation in accordance with right hand screw rule. Hence angular momentum is an axial vector.

L⃗ =r⃗ ×p⃗ 

Answer : Option A
Explaination / Solution:

The surface tension of a liquid results from an imbalance of intermolecular attractive forces, the cohesive forces between molecules:A molecule in the bulk liquid experiences cohesive forces with other molecules in all directions.A molecule at the surface of a liquid experiences only net inward cohesive forces.The unbalanced attraction of molecules at the surface of a liquid tends to pull the molecules back into the bulk liquid leaving the minimum number of molecules on the surface. It required energy to increase the surface area of a liquid because a larger surface area contains more molecules in the unbalanced situation and this may results as the surface being stretched.

Answer : Option C
Explaination / Solution:

for 1 mole of ideal gas, according to ideal gas equation

PV=RTPVT=R=const.$\begin{array}{r}.\end{array}$

hence graph must be with zero slope. So that dotted line show ‘ideal’ gas behavior and curved line shows deviation from ‘ideal’ gas behavior

A real gas behave as ideal gas at high temperature. Temperature T1 is close to dotted line. 

so that T1 > T2

 

Answer : Option D
Explaination / Solution:

rate of flow of heat H depends on

H∝AH∝ΔTH∝1L

hence H∝AΔTL

H=KAΔTL

K =  thermal conductivity of the material

Answer : Option D
Explaination / Solution:

if an equation fails this consistency test, it is proved wrong, but if it passes, it is not proved right. Thus, a dimensionally correct equation need not be actually an exact (correct) equation, but a dimensionally wrong (incorrect) or inconsistent equation is definitely wrong.

Answer : Option D
Explaination / Solution:
No Explaination.

Answer : Option A
Explaination / Solution:

When velocity – time graph is plotted for an object moving with uniform acceleration, the slope of the graph is a straight line. 

Answer : Option C
Explaination / Solution:
No Explaination.

Answer : Option A
Explaination / Solution:

The escape velocity is the minimum velocity required to leave a planet or moon. For a rocket or other object to leave a planet, it must overcome the pull of gravity.

Vescape=2GMR−−−−√

Vescape=11184 m/sec approximate to 11.2 km/sec

Answer : Option C
Explaination / Solution:

In order to make vectors a + b + c + d = 0, it is not necessary to have all the four given vectors to be null vectors. There are many other combinations which can give the sum zero. (b) Correct a + b + c + d = 0 a + c = – (b + d) Taking modulus on both the sides, we get: | a + c | = | –(b + d)| = | b + d | Hence, the magnitude of (a + c) is the same as the magnitude of (b + d). (c) Correct a + b + c + d = 0 a = – (b + c + d) Taking modulus both sides, we get: | a | = | b + c + d | | a | ≤ | a | + | b | + | c | ..... (i) Equation (i) shows that the magnitude of a is equal to or less than the sum of the magnitudes of b, c, and d. Hence, the magnitude of vector a can never be greater than the sum of the magnitudes of b, c, and d. (d) Correct For a + b + c + d = 0 a + (b + c) + d = 0 The resultant sum of the three vectors a, (b + c), and d can be zero only if (b + c) lie in a plane containing a and d, assuming that these three vectors are represented by the three sides of a triangle. If a and d are collinear, then it implies that the vector (b + c) is in the line of a and d. This implication holds only then the vector sum of all the vectors will be zero.