How is the radioactivity of a radio isotope affected if it undergoes a chemical change? Give a reason for your answer.

(a) Which nuclear radiation will travel undeviated in an electric field? (b) How can one stop the radiations escaping from a nuclear reactor in a nuclear power plant? (c) Name one internal source of background radiations.

(a) Complete the following nuclear changes: (b) Name the nuclear radiation which has the highest ionizing power.

A block and tackle system of pulleys has velocity ratio 4. (a) Draw a labelled diagram of the system indicating clearly, the direction of the load and the effort. (b) What is the value of the mechanical advantage of the given pulley system if it is an ideal pulley system?

Which of the following radiations suffer maximum deflection in a magnetic field? (a) Alpha radiations (b) Beta radiations (c) Gamma radiations (d) X-radiations

(a) In the following atoms, which one is a radioisotope? Give one use of it. O-16, C-14, N-14, He-4 (b) Name the class of the lever shown in the picture below:

Meera chose to use a block and tackle system of ‘9’ pulleys instead of a single movable pulley to lift a heavy load. (a) What is the advantage of using a block and tackle system over a single movable pulley? (b) Why should she connect more number of pulleys in the upper fixed block?

Copy and complete the nuclear reaction by filling in the blanks.

Give two differences between nuclear fission and nuclear fusion.

A radioactive element is kept in an evacuated chamber. The rate of radioactive emission will: (a) decrease (b) increase (c) remain unchanged (d) depend on the temperature

Complete the following by choosing the correct answers from the bracket: (a) In uniform circular motion the centrifugal force acts ............... [towards the centre/away from the centre/along the tangential direction]. (b) Refractive index of a medium is independent of ............... [temperature/angle of incidence/wavelength of light]. (c) Heat absorbed during change of phase depends on ............... [mass/change in temperature/specific heat capacity] of the substance. (d) Emf of a cell is ............... [greater than/less than/equal to] the terminal voltage when the cell is in open circuit. (e) In a step-up transformer the turns ratio is ............... [more than 1/less than 1/equal to 1]. (f) The nuclear radiation with lowest ionising power is ............... [α/β/γ].

Which of the following is a class III lever? (a) Pair of scissors (b) Wheelbarrow (c) Crowbar (d) Human forearm