An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.

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?

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?

Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.

Describe double circulation of blood in human beings. Why is it necessary?

What is an homologous series? Explain with an example.

Give an example of a double displacement reaction other than the one given in activity 1.10.

Calculate the number of electrons constituting one coulomb of charge.

Suggest some approaches towards the conservation of forests.

Where do plants get each of the raw materials required for photosynthesis?

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

You are given kerosene, turpentine and water. In which of these does the light travel fastest? Use the information given in Table 10.3.