Explain the following :
(i) A balloon collapses when air is removed from it.
(ii) Water does not run out of a dropper unless its rubber bulb is pressed.
(iii) Two holes are made in a completely filled sealed tin can to take out oil from it.

Water does not run out of a dropper unless its rubber bulb is pressed.

Two holes are made in a sealed tin can to take out oil from it. Explain.

The diagram shows a force extension graph for a rubber band, consider the following statements (I). It will be easier to compress this rubber than expand it. (II). Rubber does not return to its original length after it is stretched. (III). The rubber band will get heated if it is stretched and released. Which of these can deduced from the graph- (a). III only (b). II and III (c). I and III (d). I only

The diagram shows a force-extension graph for a rubber band. Consider of the following statements I. It will be easier to compress this rubber than expand it II. Rubber does not return to its original length after it is streched III. The rubber band will get heated id it is streched and realeased Which of these can be deduced from the graph

A large open tank has two holes in the wall. One is square hole of side L at a depth y from the top and the other is a circular hole of radius R at a depth of 4y from the top. When the tank is completely filled with water, the quantities of water flowing out per second from both holes are the same. Then R is equal to

A large open tank has two holes in the wall. One is a square hole of side L at a depth y from the top and the other is a circular hole of radius R at a depth 4y from the top. When the tank is completely filled with water, the quantities of water flowing out per second from both holes are the same. Then, R is equal to

Fill up the blanks in the following paragraph by selecting the correct option. The movement of air into and out of the lungs is carried out by creating a (i).____ between the lungs and the atmosphere. Inspiration can occur if intra-pulmonary pressure is (ii).____ Expiration takes place when the intra-pulmonary pressure is (iii).____ than the atmospheric pressure. Expiration takes place when the intra-inspiration is initiated by the (iv).____ of diaphragm which (v).____the volume of thoracic chamber in the antero-posterior axis.

Which of the following statements are true (T) and which are false (F)? (i) Sum of the three sides of a triangle is less than the sum of its three altitudes. (ii) Sum of any two sides of a triangle is greater than twice the median drawn to the third side. (iii) Sum of any two sides of a triangle is greater than the third side. (iv) Difference of any two sides of a triangle is equal to the third side. (v) If two angles of a triangle are unequal, then the greater angle has the larger side opposite to it. (vi) Of all the line segments that can be drawn from a point to a line not containing it, the perpendicular line segment is the shortest one.

Which of the following statements is/are incorrect ? (i) The liver fluke, a parasite, depends on intermediate hosts (a snail) to complete its life cycle. (ii) The malarial parasite needs a vector (mosquito) to spread to other host organisms. (iii) In case of brood parasitism, the eggs of parasitic birds are not detected and removed from the nest because the parasite's eggs resemble the host's eggs in morphology and colour. (iv) A population of frogs protected from all predators would increase indefinitely.

Explain the following giving reasons : (i) When monochromatic light is incident on a surface separating two media, the reflected and refracted light both have the same frequency as the incident frequency. (ii) When ligjt travels from a rarer to a denser medium, the speed decreases. Does this decrease in speed imply a reduction in the energy carried by the wave ? (iii) In the wave picture of light, intensity of light is determined by the square of the amplitude of the wave. What determines the intensity in the photon picture of light ?