Percentage error, \(\delta d=\left( \frac { \triangle \bar { d } }{ d } \times 100 \right) \)%
= 0.0256 x 100% = 2.56% = 2.6%

3.46 x 10⁶m

Angular diameter of moon is the angle subtended at a point on the earth, by two diametrically opposite ends of the moon. Its value is about 0.5⁰ .

In 1 teragram = 10¹²g
In 1 metric ton = 10³kg = 10³ x 10³ = 10⁶g
Number of metric tons are in teragram
\(\frac { { 10 }^{ 12 }g }{ { 10 }^{ 6 }g } ={ 10 }^{ 6 }\)

Here, Z = \(\frac { { A }^{ 4 }{ B }^{ 1/3 } }{ { CD }^{ 3/2 } } \)
Relative error, \(\frac { \triangle Z }{ Z } \)
\(\\ =\pm \left[ 4\left( \frac { \triangle A }{ A } \right) +\frac { 1 }{ 3 } \left( \frac { \triangle B }{ B } \right) +\left( \frac { \triangle C }{ C } \right) +\frac { 3 }{ 2 } \left( \frac { \triangle D }{ D } \right) \right] \)

Three

nm stands for nanometer, 1 nm = 10^-9 m, mN stands for milli-newton, 1 mN = 10^-3 N, Nm stands for newton metre. 

No, since length is fundamental quantity and velocity is the derived quantity.

Given, time delay between generation of a wave and the reception of its echo (T)  = 77. 0s
The generation wave moves through water and strikes the objects under water. After striking with objects, these waves are reflected back.
Time delay between generation of a wave and the reception of its echo = 2 x time taken by the wave to reach the enemy submarine.
Time taken by the reach the enemy submarine
t = \(\frac { T }{ 2 } =\frac { 77.0 }{ 2 } s=38.5s\)
Speed of sound in water (v) = 1450 m/s
Distance of enemy submarine (D) = v x t
= 1450 x 38.5
= 55825
= 55.825 km

The number of significant figures in the given quantities are given below.
(i) In 0.007, the number of significant figures is 1 because in a number less than 1, the zero's on the right of the decimal point but to the left of the first non-zero digit are not significant.
(ii) In 2.64 × 10²⁴ kg, the number of significant figures is 3 because all non-zero digits are significant, power of 10 are not taken in significant figure.
(iii) In 0.2370, the number of significant figures is 4, as all non-zero digits left to decimal and trailing zero are significant.
(iv) In 6.320, the number of significant figures is 4, as all non-zero digits left to decimal and trailing zero are significant.
(v) In 6.032, the number of significant figures is 4, as all non-zero digits left to decimal and trailing zero are significant.
(vi) In 0.0006032, the number of significant figures is 4, because in a number less than 1, the zero's on the right of the decimal point but to the left of the first non-zero digit are not significant.