Which of the following are correct structural isomers of butane?
Answer: (c) (i) and (ii) Chemical compounds that have identical chemical formulae but differ in properties and the arrangement of... View Article
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Buckminsterfullerene is an allotropic form of (a) phosphorus (b) sulphur (c) carbon (d) tin
Answer: (c) carbon Buckminsterfullerene (C60) or buckyball is one of the allotropes of carbon. The structure of fullerene is like... View Article
A molecule of ammonia (NH3 ) has (a) only single bonds (b) only double bonds (c) only triple bonds (d) two double bonds and one single bond
Answer: (a) only single bonds Nitrogen has three electrons in its outermost shell and hydrogen has 1. 3 hydrogen atoms... View Article
Which of the following statements are usually correct for carbon compounds? These (i) are good conductors of electricity (ii) are poor conductors of electricity (iii) have strong forces of attraction between their molecules (iv) do not have strong forces of attraction between their molecules (a) (i) and (iii) (b) (ii) and (iii) (c) (i) and (iv) (d) (ii) and (iv)
Answer: (d) (ii) and (iv) Because accepting and donating four electrons is difficult, carbon forms only covalent bonds. Because they... View Article
Carbon exists in the atmosphere in the form of (a) carbon monoxide only (b) carbon monoxide in traces and carbon dioxide (c) carbon dioxide only (d) coal
Answer: (c) carbon dioxide only Carbon is found in the atmosphere as carbon dioxide gas in the air. Carbon can... View Article
Two ores A and B were taken. On heating ore A gives CO2 whereas, ore B gives SO2. What steps will you take to convert them into metals?
Answer: Ore A gives CO2 on heating hence it is a carbonate ore. Steps involved in extraction of ore A... View Article
An element A burns with golden flame in the air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.
Answer: Element A is Sodium because it will burn with a golden flame in the air. Element B is Chlorine... View Article
Of the three metals X, Y and Z. X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.
Answer: X is an alkali metal, Na or K. Y is an alkaline earth metal, Mg or Ca. Z is... View Article
Draw a neat and well-labelled diagram for electrolytic refining of copper
Answer: Electrolytic refining is a technique that is used for the extraction and purification of metals that are obtained by... View Article
Given below are the steps for extraction of copper from its ore. Write the reaction involved. (a) Roasting of copper (1) sulphide (b) Reduction of copper (1) oxide with copper (1) sulphide. (c) Electrolytic refining
Answer: (a) Roating is basically a process of metallurgy where ore is converted into its oxide by heating it below... View Article
Explain why the metals like Na, K, Ca and Mg are never found in their free state in nature.
Answer: Metals such as Na, K, Ca, and Mg are never observed in their free state since they are very... View Article
Explain why the iron articles are galvanised. (e) Metals like Na, K, Ca and Mg are never found in their free state in nature.
Answer: Galvanising is a method of rust prevention. The iron or steel object is coated in a thin layer of... View Article
Explain why the NaCl is not a conductor of electricity in the solid-state whereas it does conduct electricity in aqueous solution as well as in molten state
Answer: Ionic solids conduct electricity in a molten state but not in solids state. This is because, in ionic compounds,... View Article
Explain why thec arbon cannot reduce the oxides of Na or Mg
Answer: Both sodium and magnesium, and also aluminium, are more reactive than carbon, according to the reactivity series, as these... View Article
Explain why the reactivity of Al decreases if it is dipped in HNO3
Answer: Reactivity of Aluminium decreases if it is dipped in HNO3 because HNO3 is a strong oxidizing agent. Here, a... View Article
Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.
Answer: During the extraction of metals of low and medium reactivity from their respective sulphide ores. They are first heated... View Article
A non-metal A which is the largest constituent of air, when heated with H2 in 1:3 ratio in the presence of a catalyst (Fe) gives a gas B. On heating with O2 it gives an oxide C. If this oxide is passed into water in the presence of air, it gives an acid D which acts as a strong oxidising agent. (a) Identify A, B, C and D (b) To which group of periodic table does this non-metal belong?
Answer: (a) Non-metal “A” is nitrogen because it is the largest constituent of air which constitute around 78% of the... View Article
A solution of CuSO4 was kept in an iron pot. After a few days, the iron pot was found to have a number of holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved.
Answer: Since iron is more reactive than copper, it displaces copper, resulting in FeSO4. A portion of the iron is... View Article
An element forms an oxide A2O3 which is acidic in nature. Identify A as metal or non-metal.
Answer: Since an element’s oxide is acidic in nature, A will be a non-metal because the acidity of non-metal oxides... View Article
A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black colour product. Identify M and black coloured product and also explain the reaction of M with oxygen.
Answer: Copper is a metal that does not react with acids. With oxygen, it forms Copper Oxide. Metal M is... View Article
