Chemistry MCQs

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Washing soda’s chemical formula is Na₂CO₃. It binds calcium and magnesium present in the water and creates an insoluble substance.

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A copper awl is the oldest metal object unearthed to date in the Middle East. The discovery reveals that metals were exchanged across hundreds of miles in this region more than 6,000 years ago, centuries earlier than previously thought, researchers say.

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Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom.

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Methyl alcohol is very dangerous. May be fatal or cause blindness if swallowed. Harmful, if inhaled or absorbed through skin. It cannot be made non poisonous. Some other harmful effects are results into irritation of skin, eyes and respiratory track. It can also effects central nervous system and liver.

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Carbon-14 (C-14) isotope which is radio active in nature is used in Carbon Dating to determine the age of plants and fossils. It has a half-life (decays to half the strength) of 5,730 years.

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In 1778, Antoine Lavoisier, considered “The father of modern chemistry”, recognized and named oxygen, and recognized its importance and role in combustion. Antoine Lavoisier discovered the relationship between oxygen and metal that leads to rust. He also proved the role of oxygen in respiration and discovered the chemical composition of water and air. Henry Cavendish discovered hydrogen in 1766 as a colorless, odorless gas that burns and can form an explosive mixture with air.

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Sting of ants and bees contains formic acid. This can be neutralized by rubbing soap, which is alkaline in nature.

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Alizarin or 1,2-dihydroxyanthraquinone (also known as Mordant Red 11 and Turkey Red is an organic compound with formula C14 H8 O4 that has been used throughout history as a prominent red dye, principally for dyeing textile fabrics. Historically it was derived from the roots of plants of the madder genus. In 1869, it became the first natural pigment to be duplicated synthetically.

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Ionization energy is a measure of the ease in which atoms lose electrons and become positive ions. The 1S2.2S2.2P2 configuration in nitrogen is more stable than 1522522P4 due to half filled p-sublevel. Hence nitrogen, N atom has greater ionization energy than oxygen, O atom.

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The type of bond formed between two atoms depends upon the difference in their electronegativities. If the difference in electronegativities is zero or very small, the bond formed would be covalent and if the difference exceeds 2.5, the bond formed would be electrovalent. In simple words, Lesser the difference in electronegativity of two atoms, the bond formed will be covalent; higher the difference, the bond formed will be electrovalent.