Questions
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Why can you smell some gases, but not others ?
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Actually, methane doesn't smell either, but you probably thought it did because it is often found with hydrogen sulphide which is very stinky and smells just like rotten eggs. Gases get into our noses to excite our olfactory (or smelling nerves) which are connected to our brains to allow us to smell. How a gas smells depends on it's size and shape, and how it can fit into our smell receptors in the nose. It also depends of course on how easily a gas evaporates. Gases which evaporate more easily smell stronger because more vapour manages to get into the nose. Gases which smell tend to be the ones which are heavier, and more than 15 times the weight of hydrogen which is the smallest atom, so methane and carbon monoxide (CO) don't smell but hydrogen sulphide (H2S), and chlorine (Cl2) do. Why does it smell when we break wind? This is because the your gut contains lots of bacteria and enzymes to digest your food and in this process gases like hydrogen sulphide (H2S) are produced. Interesting fact - we break wind on average 14 times a day. However a word of warning, if the concentration of hydrogen sulphide increases too much, your olfactory, or smelling, nerves are paralysed and you lose the ability to smell it. Other gases which don't smell are Oxygen, Nitrogen, and steam. Gases which do smell include chlorine, bromine, iodine and sulphur dioxide.
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Where does the rainbow end ?
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Disappointing news for Billy - the rainbow doesn't touch the ground and there is no end to it. Light from the sun looks white, but it is actually made of lots of different colours. Normally they are all mixed together. Arainbow is formed when light from the sun meets raindrops in the air and the raindrops separate out all these different colours. Because rainbows are made in the sky they don't touch the ground. So if you're on the ground, however far you walk, the end of the rainbow will always look as if it were on the edge of the horizon. But what people don't realise is that rainbows are actually complete circles, and obviously a circle has no end. You never see the whole circle because the earth's horizon gets in the way. Apparently if you see a rainbow from a plane it should be almost a complete circle. Another interesting fact about rainbows - have you ever noticed that you'll only ever see a rainbow if the sun is behind you? You can also sometimes see miniature rainbows in your garden if you're watering your plants with the sun behind you.
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| Fact or Fiction
Most monkeys have evidence of broken bones caused by falling out of trees
 
![]() It's True Researchers in Japan studying the skeletons of macaques killed by local farmers because they were raiding their crops found that half of the monkeys had healed fractures with the males having the most. Since these monkeys rarely fight, and there were no signs of bite marks, the researchers conclude that the injuries must have been sustained by falling out of trees ! Not quite the aerial acrobats we thought they were !
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There is a gene that makes people avoid eating vegetables
![]() It's True According to recent research 25% of the population are 'supertasters' and carry a gene that increases the number of taste buds on the tongue, causing them to dislike the bitter taste of greens, broccoli and tomatoes. As well as causing them to avoid eating healthy vegetables, which dramatically increases their chances of developing bowel cancer, these people also avoid coffee, sweet and high-fat foods, and chillies !
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Most children cannot blow their nose before the age of 5
![]() It's True Actually a massive 60% of children cannot do this. Although most children of 5 can recite nursery rhymes, brush their hair and teeth and do up buttons, fewer than 40% of them are sufficiently co-ordinated to blow their noses - most either forget to close their mouth or do not squeeze their nose at the right time. And the alternative ? The majority just give up and use their sleeves, according to recent survey of 503 children. The study also found that the only skill more difficult to master is tying shoe laces which most children do not manage until they are 6.
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