Advertisements
Advertisements
प्रश्न
Write equations for the reactions of calcium and potassium with water.
उत्तर
The reaction of calcium with water is exothermic, but the heat that evolved is not sufficient for the hydrogen to catch fire.
\[\ce{Ca_{(s)} + 2H2O_{(l)} -> Ca(OH)2_{(aq)} + H2_{(g)}}\]
Calcium starts floating because bubbles of hydrogen gas form and stick to the surface of the metal.
Potassium reacts violently with cold water, and its reaction is so violent and exothermic that the evolved hydrogen immediately catches fire.
\[\ce{2K_{(s)} + 2H2O_{(l)} -> 2KOH_{(aq)} + H2_{(g)}}\]
APPEARS IN
संबंधित प्रश्न
A solution of CuSO4 in water is .................... in colour.
(a) Pink
(b) Blue
(c) Colourless
(d) Green
What will happen if a strip of zinc is immersed in a solution of copper sulphate?
Fill in the following blank with suitable word:
Magnesium liberates ............... gas on reacting with hot boiling water.
What type of oxides are formed when metals combine with oxygen? Explain with the help of an example.
What happens when magnesium reacts with very dilute nitric acid? Write an equation for the reaction involved.
A copper plate was dipped in AgNO3 solution. After certain time, silver from the solution was deposited on the copper plate. State the reason why it happened. Give the chemical equation of the reaction involved.
Write the equation for the reaction of Magnesium with dilute hydrochloric acid.
Name the products formed. Also indicate the physical states of all the substances involved.
Name one metal which displaces silver from silver nitrate solution and one which does not.
The elements whose oxides can turn phenolphthalein solution pink are:
(a) Na and K
(b) K and C
(c) Na and S
(d) K and P
One of the following is not a neutral oxide. This is:
(a) CO
(b) H2O
(c) N2O
(d) Na2O
Out of aluminium, copper, calcium and tin, the most reactive metal is:
(a) aluminium
(b) copper
(c) tin
(d) calcium
Which one of the following four metals would be displaced from the solution of its salt by the other three metals?
(a) Zn
(b) Ag
(c) Cu
(d) Mg
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.
What are noble gases
Write the chemical equation of the above process.
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?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
Metals are generally solid. Which of the following metals is in the liquid state at room temperature?
Which of the following property is not responsible for copper to be used as electrical conduction wires?
