Advertisements
Advertisements
Question
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:
Options
calcium
carbon
silicon
iron
Advertisements
Solution
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.
\[\ce{2Ca + O2 -> 2CaO}\]
\[\ce{CaO + H2O -> \underset{(soluble)}{\underset{Calcium hydroxide}{Ca(OH)2}}}\]
RELATED QUESTIONS
Write the electron-dot structures for sodium, oxygen and magnesium.
Show the formation of Na2O by the transfer of electrons.
What will happen if a strip of copper is kept immersed in a solution of silver nitrate (AgNO3)?
Complete and balance the following equation:
Cu (NO3)2 (aq) + Zn(s) →
Which gas is produced when dilute hydrochloric acid is added to a reactive metal?
Name two metals (other than zinc and iron) which can displace hydrogen from dilute hydrochloric acid?
You are given samples of three metals − sodium, magnesium and copper. Suggest any two activities to arrange them in order of their decreasing reactivities.
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?
What is meant by the reactivity series of metals? Arrange the following metals in an increasing order of their reactivities towards water:
Zinc, Iron, Magnesium, Sodium
Name one metal more reactive and another less reactive than hydrogen.
The elements whose oxides can turn litmus solution red are:
(a) lithium and sodium
(b) copper and potassium
(c) carbon and hydrogen
(d) phosphorus and sulphur
State and explain the reaction, if any, of the following metals with a solution of copper sulphate:
(a) Gold
(b) Copper
(c) Zinc
(d) Mercury
When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so?
A zinc plate was kept in a glass container having CuSO4 solution. On examining it was found that the blue colour of the solution is getting lighter and lighter. After a few days, when the zinc plate was taken out of the solution, a number of small holes were noticed in it. State the reason and give chemical equation of the reaction involved.
Choose the correct alternative and rewrite the following:
Which of the following is lue in colour?
Calcium floats over water during the reaction with water. Give reason.
Write the chemical equation for the following reaction:
Cinnabar is heated in the presence of air.
Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
- Good thermal conductivity
- Good electrical conductivity
- Ductility
- High melting point
Why is acidified water considered to be a good conductor of electricity?
