Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?

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?

Name the substance which on treatment with chlorine yields bleaching powder.

Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.

What change will you observe if you test soap with litmus paper (red and blue)?

Why is respiration considered an exothermic reaction? Explain.

What is the function of digestive enzymes?

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

A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω , 0.5 Ω and 12 Ω, respectively. How much current would flow through the 12 Ω resistor?

Give two important uses of washing soda and baking soda.

Write equations for the reactions of

   (i) iron with steam
   (ii) calcium and potassium with water.

What will happen if a solution of sodium hydrocarbonate is heated? Give the equation of the reaction involved.