Correct Answer: B. drainage

Correct Answer: B. Propanal and propanone

Explanation

(a) Activities of man that pollute water bodies are:

(1) dumping of household refuse or organic wastes into water bodies

(ii) oil spillage from drilling or tankers

(iii) thermal pollution, hot water from industrial plants and atomic reactors

(iv) dumping of agro chemicals, e.g. fertilizers, pesticides, fungicides etc

(v) dumping of dye from textile factories into water

(vi) pouring detergents from homes and factories into water bodies

(vii) pouring tannins from leather factories into water bodies

(viii) radiations or radioactive fall-outs from nuclear plants washed into water bodies

(ix) untreated sewage dumped into water bodies

(x) use of dynamites/explosives for fishing

(xi) use of chemicals (Gamalin/DDT) in fishing.

(b) Measures for preventing pollution of water bodies are:

(1)Treatment of raw sewage before discharging into water and prohibition of disposal of human waste into water bodies

(2)Refuse must be burnt or buried and must not be deposited into water bodies

(3)Recycling of industrial waste before discharging them into water.

(4) Wastes should be discharged in controlled amounts.

(5) Cooling of water from industrial plants before discharging

(6) Proper sewage treatment

(7) Using biodegradable detergents in controlled amounts

(8) Limiting the use of pesticides and fertilizers

(9) Spraying oil with detergents to spread it or cover oil with chalk powder to cause it to sink and speed up bacteria decomposition/efficient method of preventing oil spillage

(10) Proper education of farmers on correct usage of fertilizers to limit run-off into water bodies

(11) Enactment/enforcement of laws to prevent the use of explosives and chemicals in fishing. The methods of purifying water are: boiling, addition of chemicals, e.g. alum, and chlorination; filtering; distillation; sedimentation and boiling; sterilization, e.g. by using u. v. light

Correct Answer: (b) Water comes on top

Explanation

(a)(i)

Mode of Operation:

In the X-ray tube a Low voltage high p.d is applied between the hot cathode and the anode. Electrons are emitted from the cathode and are accelerated to an extremely high speed. They are suddenly decelerated when they strike the anode causing the emission of high - energy radiation of short wavelength - X-ray. In this process the anode becomes very hot, and requires cooling fins on the outside of the tube.

Energy Transformation: The electrons have kinetic energy which is partly changed to internal energy (potential) and finally changed to heat energy.

(b) Hardness: Refers to X-rays with high penetrating power, short wavelength but high frequency. They are produced by increasing the p.d. between the cathode and anode. Such X-rays are called hard X-rays. Less penetrating or lower frequency ones are called soft X-rays. They are produced at lower p.d.

Intensity: High intensity X-rays beam results from the increase of current through the filament which leads to increase in the number of electrons.

(c)(i) Uses of X-rays:

(1) Investigating the structure of crystals ; (2) X-ray examination of the body for broken bones; (3) As invincible bullets for the treatment of tumours ; (4) Examination of metals for defects and fractures.

(ii) They may cause damage to living tissue and to cells. Precaution to be taken includes lead screening and regular health checks.

Correct Answer: B. a variable cost

Correct Answer: C. N2O

Correct Answer: D. Rivers, Delta and Kaduna

Correct Answer: A. Needs

Correct Answer: C. Paul had not obtained Philemon's consent