Define the unit of current.

When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.

Outline a project which aims to find the dominant coat colour in dogs.

Draw the structure for the following compounds.                

       (i)    Ethanoic acid             (ii)   Bromopentane*
       (iii)  Butanone                   (iv)   Hexanal.

*Are structural isomers possible for bromopentane?

A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?

How is the sex of the child determined in human beings?

(a)  What property do all elements in the same column of the Periodic Table as boron have in common?
(b)  What property do all elements in the same column of the Periodic Table as fluorine have in common?

Calculate the number of electrons constituting one coulomb of charge.

What is an homologous series? Explain with an example.

Why is variation beneficial to the species but not necessarily for the individual?

A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?

Why should we conserve forests and wildlife?

What does one mean by exothermic and endothermic reactions? Give examples.

The radius of curvature of a spherical mirror is 20 cm. What is its focal length?

Why does the cord of an electric heater not glow while the heating element does?

A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is

   (a) towards south                 (b) towards east
   (c) downward                       (d) upward

What is the need for a system of control and coordination in an organism?

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

How is the concentration of hydronium ions (H₃O⁺) affected when a solution of an acid is diluted?

How is the equal genetic contribution of male and female parents ensured in the progeny?

Why is respiration considered an exothermic reaction? Explain.