A convex mirror is used as a driving mirror because

I. its image is erect

II. It has a large field of view

III. It has a long focal length

Identify the CORRECT statement(s)

• A. I and III only
• B. I and II only
• C. II and IIII only
• D. I, II and III only

(a) Define specific latent heat of vaporization.

(b) (i) What are renewable energy sources?

(ii) List four renewable energy sources.

(c) Explain why tomatoes keep longer when kept in a moist jute bag in a clay pot.

(d) A box has a volume of 0.28 m\(^3\) and is 70% filled with iron fillings at 25°C. Calculate the:

(i) total mass of the iron fillings;

(ii) energy required to melt 10% of the iron fillings. [Density of iron = 8.00 x 10\(^3\) kgm\(^{-3}\); specific latent heat of fusion of iron = 1.38 x 10\(^5\) Jkg\(^{-1}\), specific heat capacity of iron = 460 Jkg\(^{-1}\) k\(^{-1}\), melting point of iron = 1500°C] 10.

The earth's gravitational field intensity at its surface is about (G = 6.7 × 10^−11Nm²/kg², mass of the earth is 6 × 10²⁴kg, radius of the earth is 6.4 × 10⁶m, g on the earth = 9.8m/s²)

• A. 6.7N/kg
• B. 7.9N/kg
• C. 8.0N/kg
• D. 9.8N/kg

When a sound wave passes from air into water its

• A. speed and frequency increases but its wavelength remains the same
• B. speed and wavelength increases but its frequency remains the same
• C. speed decreases
• D. speed increases but its frequency and wavelength decreases

A black body radiates maximum energy when its surface temperature T and the corresponding wavelength \(\lambda\)max are related by the equation \(\lambda\)max T = constant. Given the values of the constant and surface temperature as 2.9 x 10\(^{-3}\) mK and 57°C respectively; Calculate the frequency of the energy radiated.

A ray of light strikes a plane mirror at an angle of incidence of 35°. If the mirror is rotated through 10°, through what angle is the reflected ray rotated?

• A. 70°
• B. 45°
• C. 25°
• D. 20°

(a) When nitrogen (atomic mass = 14, atomic number = 7) is bombarded with neutrons, the collisions result in disintegrations in which alpha particles are produced. Represent this transmutation in a symbolic equation.

(b)(i) How does a radioactive atom differ from a stable one?

(ii) Explain 'half life'.

(iii) A sample of radioactive material has a haft life of 35 days. Calculate the fraction of the original quantity that will remain after 105 days.

(c) Light of wavelength 5.00 x 10\(^{-7}\)m is incident on a material of work function 1.90 eV. Calculate

(i) photon energy.

(ii) kinetic energy of the most energetic photo electron.

(iii) stopping potential [Plancks constant h =6.6 x 10\(^{-34}\)Js] [c= 3.0 x10\(^8\)ms\(^{-2}\), leV= 1.6 x 10\(^{19}\)J]

Which of the following quantities has the same unit as energy?

• A. power
• B. work
• C. force
• D. momentum

Aluminium is sometimes used as the leaf of an electroscope because it

• A. is a light material
• B. is a good conductor
• C. is a good insulator
• D. can be converted into thin sheets

Which of following functions is performed by manganese IV oxide in the Lenclanche cell?

• A. control of local action
• B. depolarisation of the cell
• C. regulating current flow in the cell
• D. reduction of the internal resistance of the cell