<span>This is false. A carbohydrate is a carbon-based molecule that can be utilized by living organisms in order to produce energy. A calorie is a unit of energy often used to measure the amount of energy within food. Another example of energy unit is the Joule, more commonly used within physics.</span>
Explanation:
21. The given molecule for cracking is tetradecane.
On cracking it forms one mole of decane (C10H22) and two moles of ethene gas.
The chemical equation is shown below:

22. The essential condition for the formation of an ester is the reaction of alcohol and acid in presence of concentrated sulfuric acid.
Thus among the given options, the first option is the correct one.
23. Isomers of butanol are shown below:
It is 2-butanol.
The position of -OH group changes to the second carbon.
Answer is: It has a negative charge and is located in orbitals around the nucleus.
The electron (symbol: e⁻) is a subatomic particle whose electric charge is negative one elementary charge.
Electrons are moving in energy levels around nucleus.
The electron has a mass that is approximately 1/1836 that of the proton.
Electrons have properties of both particles and waves.
Explanation:
When water vapour changes to liquid water then this process is known as condensation.
For example, when lid is placed in a hot water filled pan then after sometime vapours appear on the surface of lid. When temperature of water decreases then water vapours convert into liquid form.
Thus, we can conclude that in condensation water vapor changes to liquid water.
Answer: Sodium + water → hydrogen gas + sodium hydroxide (aq) + heat [(aq) means “dissolved in water”. It stands for “aqueous”.] If we boil off the water, we will be able to see the sodium hydroxide crystals. The sodium hydroxide is one of the two new substances produced by this chemical change.