If a woman is using a copper -T, will it help in protecting her from sexually transmitted diseases?

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?

What are plant hormones?

What is the importance of DNA copying in reproduction?

Why does an aqueous solution of an acid conduct electricity?

The xylem in plants are responsible for

         (a) transport of water.                   (c) transport of amino acids.
         (b) transport of food.                     (d) transport of oxygen.

Explain the importance of fossils in deciding evolutionary relationships.

What would be the consequences of a deficiency of haemoglobin in our bodies?

Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.

An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be –

(a) 100 W          (b) 75 W          (c) 50 W          (d) 25 W

The anther contains

(a) sepals.
(b) ovules.
(c) pistil.
(d) pollen grains.

What are the differences between autotrophic nutrition and heterotrophic nutrition?