Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
Decompositive reaction in presence of Heat:
2Pb(NO3)2 (s) -- Heat → 2PbO (s) + 4NO2(g) + O2(g)
Lead Nitrate Leadoxide Nitrogen dioxide Oxygen
Decompositive reaction in presence of Light:
2AgCl - Light→ 2Ag + Cl2 gas
Silver Chloride (white) (grey)
Decompositive reaction by the use of electricity:
2H2O (l) -- Electricity→ 2H2 (g) + O2 (g)
water hydrogen gas oxygen 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?
A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?
Explain the formation of scum when hard water is treated with soap.
How is the equal genetic contribution of male and female parents ensured in the progeny?
One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.
Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above.
Name two metals which are found in nature in the free state.
Why do acids not show acidic behaviour in the absence of water?
What are the differences between autotrophic nutrition and heterotrophic nutrition?
Which metals do not corrode easily?
Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.