The severity of an earthquake can be measured either by measuring its magnitude or intensity. Magnitude is a measure of the strength of an earthquake at its source. It is assessed on an 8-point scale called the Richter Scale. Devised in 1935, by an American geophysicist, Charles Richter, the scale assigns a number to an earthquake depending on its strength. The Richter magnitude is calculated by using information obtained from a seismograph — the instrument that records an earthquake’s ground motion.
Intensity is a measure of the local effect caused by an earthquake which varies according to distance from the source of the earthquake. The intensity is measured in the Mercalli scale, formulated originally by an Italian seismologist Giuseppe Mercalli. The scale was subsequently modified and is still used as the Modified Mercalli Intensity Scale (MM). It classifies earthquake into 12 categories ranging from 1 (not felt except by few) to 12 (total destruction).
The shine of a surface depends on its smoothness. Smoother the surface, more it will reflect light and thus will appear shiny. Unpolished leather does not shine because its surface is full of tiny pores and is rough. When we apply polish on this rough surface, the wax in the polish fills up the very small microscopic pits of the leather surface. Vigorous brushing or rubbing with a soft cloth spreads the wax evenly by melting. This makes the surface shine. If the shoe is rubbed after a few drops of water is sprinkled on it, it shines even more because the cloth surface after absorbing little water does not stick to the wax on the leather surface but glides smoothly. Liquid shoe polishes do not need rubbing as these leave a quick drying film on the leather which itself is reflecting and gives a glossy look. 
Curd is formed by a chemical reaction which involves casein, the protein that occurs in milk. The coagulation of this protein results in the formation of curd. This occurs if bacteria called Lactobacillus acidophilus is present in milk. This bacterium produces lactic acid by the fermentation of the milk sugar lactose. The lactic acid so formed by the bacterial action contains positive hydrogen ions which are attracted to the negative particles of the protein casein. As the latter are neutralized, these protein molecules no longer repel one another but coagulate. The optimum temperature at which Lactobacillus acts is around 40°C. So milk is usually warmed to this temperature before setting it to curdle. 
The naphthalene balls used for keeping away harmful insects from damaging clothes are basically volatile chemicals having a strong odour. These compounds include a wide variety of aromatic chemicals which are mainly derived from petroleum and coal tar. These chemicals are toxic. As they are highly volatile, they produce vapours which repel insects such as moths and silverfish which damage clothes during storage.
Wool fibres are made of a particular protein (Keratin) which is a bad conductor of heat and as a result does not allow body heat to escape. This helps us in keeping warm during winter. These fibres are wavy in structure, the property commonly known as crimp. Crimp imparts resilience to the fibre due to which fibres quickly recover from wrinkling and crushing. Because of this wavy structure the fibres do not come perfectly close and as a result a large number of air pockets are formed. The air entrapped within these pockets acts as an insulator and traps body heat inside.