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प्रश्न
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be:
विकल्प
calcium
carbon
silicon
iron
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उत्तर
calcium
Explanation:
Calcium (Ca) combines with oxygen to form Calcium oxide (CaO) with a very high melting point. It dissolves in water to form Calcium hydroxide.
\[\ce{2Ca + O2 -> 2CaO}\]
\[\ce{CaO + H2O -> \underset{(soluble)}{\underset{Calcium hydroxide}{Ca(OH)2}}}\]
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संबंधित प्रश्न
A solution of CuSO4 in water is .................... in colour.
(a) Pink
(b) Blue
(c) Colourless
(d) Green
_________ solution is blue in colour.
(a) CuSO4
(b) FeSO4
(c) ZnSO4
(d) Al2(SO4)3
Name the following:
Metals which forms an amphoteric oxide.
‘E’ is an element which reacts with oxygen to form an oxide E2O. An aqueous solution of E2O turns red litmus blue, so:
i. What is the nature of oxide E2O ?
ii. Write the name of element ‘E’.
Write the chemical reaction when iron reacts with dilute H2SO4.
Food cans are coated with tin and not with zinc because ______.
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
What type of oxides are formed when non-metals react with oxygen? Explain with an example.
Write the chemical equation of the reaction which takes place when iron reacts with dilute sulphuric acid. What happens when the gas produced is ignited with a burning matchstick?
Write the equation for the reaction of Zinc with dilute hydrochloric acid.
Name the products formed. Also indicate the physical states of all the substances involved.
Hydrogen is not a metal but still it has been assigned a place in the reactivity series of metals. Why?
Name one metal more reactive and another less reactive than hydrogen.
A metal less reactive and another metal more reactive than hydrogen are:
(a) aluminium and lead
(b) iron and magnesium
(c) copper and tin
(d) copper and mercury
Which of the following reactions will not occur? Why not?
(a) MgSO4 (aq) + Cu (s) → CuSO4 (aq) + Mg (s)
(b) CuSO4 (aq) + Fe (s) → FeSO4 (aq) + Cu (s)
(c) MgSO4 (aq) + Fe (s) → FeSO4 (aq) + Mg (s)
If A, B, C, D, E, F, G, H, I, J and K represent metals in the decreasing order of their reactivity, which one of them is most likely to occur in a free state in nature?
Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?
An alkali metal A gives a compound B (molecular mass = 40) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the reaction involved.
