Can vehicle tyres be filled with liquid instead of air?

Vehicles are filled with air to absorb the shocks generated as the vehicle moves on uneven roads, and make the ride comfortable.The shock absorbing capacity is present by the fundamental property of air i.e compressibility - air can be compressed to smaller volumes on application of pressure.

But liquid is not compressible and so if one uses it to fill the tyres, all the shocks generated on the tyres will be completely passed on the vehicle and its passengers will feel the discomfort.In addition liquid filled tyres increase the rolling resistance  of vehicles because of the increase in weight. Hence a part of the engine's power and fuel is wasted in overcoming this resistance.

What is ozonised mineral water?

Ozone is a blue gas with a relative molar mass of 48 and molecular formula of O3.It converts into oxygen after oxidizing process is complete.Ozone is the ultimate Eco-friendly disinfectant. Like when drinking water is treated with Chlorine (which is found to be highly carcinogenic chemical) ,the residual chlorine is consumed with the water.On the other hand residual ozone,having a half life of only 20 minutes reduces to oxygen, leaving behind pure and safe drinking water.
Another added advantage of using ozone is that it destroys all the micro organisms leaving behind colourless and odourless water.
Ozone generators produce ozone by passing oxygen through electric field.This ozone is bubbled through the water to be treated in a specially designed apparatus with controlled rate of injection.The amount of ozone diffused in water is directly proportional to the contamination of water.  

Why is fire hot?

Chemical reactions can be either exothermic(heat liberating) or endothermic(heat absorbing).Oxidation reactions are exothermic and reduction reactions are endothermic. Combustion is an oxidation reaction and hence is exothermic.
                                                 
All liquid, solid, and gaseous fuels contain any one of the three combustibles constituents viz. carbon, hydrogen, and sulphur. When fuel is burnt the heat liberated makes the products of combustion hot. The products of combustion are carbon dioxide, water vapour and sulphur dioxide. Along with these, the unused oxygen in the atmospheric air supplied for combustion and also the entire quantity of nitrogen which is the major constituent in the air are also heated. That is why fire is hot.

How does ballast-less track provide safe travel?

Ballast is a prime component of the track that acts as a vibrant medium to transmit from the rail surface the weight of the train down to the formation, the wells set on prepared terrain. It ensures a cushioned and smooth run for the train and precludes the longitudinal displacement of the rail called creep. In ballast-less track, as the name suggests the ballast is replaced by a bed of concrete.
          The rails rest on rubber pads placed over concrete sleepers, which are fixed on the concrete bed. The ballast-less track helps to eliminate the evils of dust and noise pollution and proves suitable for underground railway also. So it is also safe for travel.

Like ordinary paints do metallic paints also fade?

Metallic paints do fade. It depends on the quality and the type of the aluminium paste used. Usually in most of the metallic paints, the commonly used pigment is aluminium pigment in the form of paste. Two types of aluminium pigments are available in the market. One is leafing, and the other is the non-leafing aluminium pigment will not get dispersed (or dispersed partially) with the resin while mixing, whereas the non-leafing will get completely dispersed with the resin during mixing.
            So, if the metallic paint contains the leafing aluminium pigment it will get faded over a period of time, whereas if it contains a non-leafing aluminium pigment it will not fade for a longer period.Example: The street lampposts on the roads and highways which are coated with metallic paints appear dull after a short period of coating, whereas cars coated with metallic paints shine even after a long time.

Why do runners run in anti-clockwise direction?

As the heart is on the left side, for humans and animals, running anticlockwise makes the centrifugal force of the body to act from left to right.Whereas it is from right to left for clockwise running.
        Superior venacava (the principal vein carrying blood to the heart) takes blood to the heart aided by heart suction.This vein carries blood from left to right.
        Centrifugal force due to anticlockwise running helps this suction.If we run clockwise, the centrifugal force impedes suction. That is why, in olden days, health officers ensured that all carnival merri-go-rounds were run only in the anticlockwise direction.
        Racing tracks, animal shows in circuses, bullock-drawn pelton wheels, all mostly have only left turns. Stairways in temple towers have only left turns for going up. Clockwise running tires people, especially, children, easily.

What is the principle of photo-chromatic glasses?

Photo-chromatic glasses become dark (activated) when kept under bright light especially when the wavelength of the incident light is in the range of 320-400 nm(nanometres).Darkened glasses get bleached when kept in the dark or under light of longer wavelenghts, 550-650 nm.Both these processes occur simultaneously during daylight and the glass's transparency depends on the predominant reaction taking place in it.
                     These processes are based on the possibility to split and recombine silver and chloride ions in silver chloride using light of different wavelenghts.It is the same principle which is used in photography also. However, in photography, the chlorine and silver ions are separated and not allowed to recombine. In photochromatic glasses, the chloride ions cannot diffuse far away from the silver ions as they are held tightly in a glass matrix. Hence when the 'activating energy' is withdrawn, they recombine to form silver halide. The speed(or rate) of the reaction depends on the doping level of the halide with a catalyst(cooper).
                   Choice of the halides, crystals' size (usually 40-100 Angstroms), concentration, glass type and sensitising dopants are all factors that decide the final behaviour of photochromatic glasses used in light-control, displays, memory applications and optical data processing.