Why do we apply paint on iron articles?
Iron articles is painted to prevent from rusting, so that iron article is do not come in contact with atmosphere oxygen and moisture. This will prevented it from rusting.
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 is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas.
Name two metals which are found in nature in the free state.
Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.
How is food transported in plants?
Name some devices in which electric motors are used.
Define 1 dioptre of power of a lens.
Why is variation beneficial to the species but not necessarily for the individual?
Name the substance which on treatment with chlorine yields bleaching powder.
How are the lungs designed in human beings to maximise the area for exchange of gases?
How is the concentration of hydroxide ions (OH-) affected when excess base is dissolved in a solution of sodium hydroxide?