Q. 255.0( 6 Votes )
An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following.
Na (sodium) possesses all the above properties. It is too soft and can be cut with a knife. It is also very reactive and reacts with oxygen or moisture present in air and produce sodium hydroxide which is highly exothermic reaction producing a lot of heat. It also reacts with water vigorously and burns due to the formation of hydrogen gas. That is why sodium is stored in kerosene oil to prevent any reaction.
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i. What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube?
ii. What type of reaction is this?
iii. Write a balanced chemical equation to represent the above reaction.
A brown substance ‘X’ on heating in air forms a substance ‘Y’. When hydrogen gas is passed over heated ‘Y’, it again changes back into ‘X’.
i. Name the substance ‘X’ and ‘Y’
ii. Name the type of chemical reactions occurring during both the changes.
iii. Write the chemical equations of the reactions.Xam idea - Science