The diagram shows a section through an alveolus. Gases diffuse through the alveolar andcapillary walls. Which row explains why gaseous exchange occurs in the alveolus? Answer: 21) D We know…
A solid sphere of radius r fits inside a hollow cylinder. The cylinder has the same internal diameter and length as the diameter of the sphere. The volume of a…
An object of mass 5kg falls from rest and hits the ground at a speed of 20m/s. Air resistance isnegligible.From what height has the object fallen? Answer: 19) B From…
A 100 % efficient transformer has 1500 turns on its primary coil. The input to the transformer is 250V ac. The output current is 10A and the output power is…
The oscillation period, t, for a spiral spring (weight w, radius R made from wire length l, radius r with a modulus of rigidity n) with a weight W hanging…
The equation for the preparation of nitrogen monoxide is:a Cu + b HNO3 ------- a Cu (NO3)2 + c H2O + 2NOWhat is the value of b? Answer: 18) D…
The three statements below are about exhaling.1 The ribs swing down and inwards during exhaling.2 The diaphragm muscles contract during exhaling.3 The pressure in the lungs increases during exhaling.Which statements…
Which of the four statements below about natural selection are correct?1 Competition occurs between individuals of the same species.2 Competition occurs between individuals of different species.3 Selection can lead to…
The equation connects the variables A, x, y, z, P and Q The following changes are made:x and y are both increased by 50 %z is decreased by 20 %P…
Evaluate: Answer: 16) F Let us break down such a complicated problem into smaller parts. (2 x 10³) = 2000(8 x 10²) = 800 So, (2 x 10³) + (8…