Can we fry food with water instead of oil?

We can not. boiling point of water is lower than oil. Food materials contain water in an occluded form or as water of hydration. We fry food essentially to remove this water. For this, the food needs to be heated beyond the boiling point of water (100 deg Celsius). If we use water as the frying medium, the water from the food cannot be removed as the medium itself gets vapourised. However, oil can be heated to more than 150 deg Celsius without charring the food. Being nonvolatile at this temperature, heat from the oil facilitates frying.

Why do lemon drops make white spots on the floor?

Lime juice contains 6-10% of citric acid. Cement is a complex mixture of calcium silicate and calcium aluminates. When drops of lime juice fall on the floor, a chemical change takes place. One of the products is calcium citrate which gives a white colour on these spots.

Ants can find their way to hidden sweets...

Antennae, the two hair-like structures on the head of the ants, help them in locating sweets. These chemoreceptors help them to perceive smell and taste through minute sensilla, or sensory cells. These sensilla can detect accurately the smell in the air. It points towards the origin of the smell by detecting accurately the changes in the concentration of the odoriferous particles. If the sweet are wrapped in paper bags or any other wrappers having minute holes, the odour carried by the air will be sensed by the sensilla. If the antenae are removed, ants cannot identify the smell and distinguish them from other foods.

Is identical twins have same fingerprints?

It is believed that the development of a unique fingerprint ultimately results from a combination of gene-environment interactions. One of the environmental factors is the intrauterine forces such as the flow of the amniotic fluid around the fetus. Because identical twins are situated in different parts of the womb during development, each fetus encounters slightly different intrauterine forces from their sibling, and so a unique fingerprint is born.

Mechanism of Remote control in TV

In earlier days, remote controls were based on Ultrasonics. The controlling circuitry included a hand held transmitter and a TV-based receiver circuit. Electronic filters and stepper motors were used to allow/select certain frequencies and perform various functions depending on the key pressed. But the recent remote controls use Infra-red rays and a special binary coding mechanism. The code, intensity and wavelength of the IR wave, help to select different functions. Depending on the key pressed, a signal is sent out by IR source, say, an injection laser diode (ILD). IT generates a code in a parallel format. This is converted to a series format by a shift register. This signal is received by photo-sensitive devices such as an avalanche photo diode at the receiver. Here another shift register is used to convert the code back to a parallel form. This operates a one-of-n-decoder, which selects one function from a set of 'n' predefined functions and executes it.

Fire is Hot?

Chemical reactions can be either exothermic (heat liberation) or endothermic (heat absorption). Oxidation reactions are exothermic and reduction reactions are endothermic. Combustion is an oxidation reaction and hence is exothermic. All liquid, solid and gaseous fuels contains any one of the three combustibles constituents viz, carbon, hydrogen and sulphur. When a fuel is burnt the heat liberated makes the products of combustion hot. The products of combustion are carbon dioxide, water vapor 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.

Why we feel sleepy while reading?

Feeling sleepy while reading for many is due to the posture in which they read. While reading a person rarely moves, this lack of physical activity causes decreased blood flow to muscles, which results in accumulation of lactic acid (a product of incomplete combustion in the cells). This lactic acid is a highly reducing or oxygen absorbing agent, which quickly reacts with oxygenated blood. This ensures lack of oxygenated blood flowing to the brain, which makes is feel sleepy. To tackle this problem we must avoid reading in a single stretch, instead its better to take some breaks and indulge in physical activity at short intervals.

We become unconscious when hit on the head

The brain is made up of millions of delicate nerve cells suspended in a clear cerebro-spinal fluid which acts as a partial shock absorber, encased inside the skull. It controls all our activities. When the head is injured in an accident the brain absorbs the force and results in a total black out and the person loses consciousness. On regaining consciousness the person will appear to be dazed and confused. this condition is temporary and termed as 'concussion'. However on receiving the blow the thick muscular flap covering the entire brain substance termed 'dura' starts to bleed or swell, then the person may become unconscious as it compresses the brain. This depends on the impact of the hit and the extend of the damage caused to the brain. This condition is termed as 'insuccession'. Noted symptoms of insuccession are: blurred vision, headache and pain in the neck region, frequent giddiness, vomiting and loss of consciousness.

Sweating before heavy rain...

Sweating, also called perspiration, is a continuous process. As the sweat glands, present below the skin, secrete sweat, it evaporated into the atmospheric air depending on the humidity (moisture content) of the air. If the air is dry (low humidity) the evaporation is fast. But, before rain, the atmospheric air is saturated with water vapour and so the evaporation of sweat slows down. As a result the sweat accumulates on the skin giving us a feeling that we sweat more.

What is the principle of breath analysers to detect drunken-driving?

Breath analyser is a device used by police to test drivers suspected of being drunk. This device use the reduction-oxidation reaction. A sample of the driver's breath is drawn into the breath analyser, where it is treated with an acidic solution of potassium dichromate. The alcohol (ethanol) in the breath is converted to acetic acid. In this reaction the ethanol is oxidised to acetic acid and the chromium in the orange-yellow dichromate ion is reduced to green chromic ion. The alcohol level in the blood is determined readily by measuring the degree of the color change from orange-yellow to green, read from a calibrated meter in the breath analyser.

What is Polaroid Sunglass?

Polaroids are thin and large sheets of crystalline polarising material capable of producing plane polarised beams of large cross section. In 1852, it was discovered by researchers that synthetic small needle shaped crystals of iodosulphate of quinine possess the property of polarizing light. These crystals are not stable. A polaroid sheet is prepared from the suspension of these crystals of nitrocellulose. To impart stability, its thin sheet is mounted between two sheets of glass or celluloid.

It can also be obtained by stretching a thin sheet of polyvinyl alcohol strained with iodine. When such a sheet is subjected to a large strain, the molecules get oriented in the direction of applied strain. If the Stretched sheet of polyvinyl alcohol is heated in the presence of a dehydrating agent such as hydrochloric acid, it becomes strongly stable. Each polaroid sheet is enclosed between thin glass plates so as to provide mechanical support.

Polaroids are of two types. H-polaroid and the k-polaroid. The main difference is that k-polaroid are not strained with iodine.