Question 1: Molecular composition is the ____________ of atoms in molecules of chemical substance.
(b) Chemical properties
(c) Type of atoms
(d) Both 1 and 3
Solution : Molecular composition is the arrangement and type of atoms in molecules of a chemical substance.
Answer : (d)
Question 2: Chemical composition is the ratio of ____________ changes occurring in chemical reaction.
(d) Both physical and chemical changes.
Solution : Chemical composition is the ratio of chemical changes occurring in chemical reaction.
Answer : (b)
Question 3: Write the empirical formula of the given molecular formula.
Answer: The empirical formula of any molecular formula represents the simplest whole number ratio of all bonded elements. Thus, the empirical formula must be:
(a) C6H6 = CH
(b) C2H5OH = C2H6O
(c) C6H12O6 = CH2O
Group of two or more atoms held together by chemical bonds is called a molecule. A molecule has specific chemical properties based on its composition and bonding. A molecule can be made up of similar or different atoms.
For example, Oxygen molecule () is made up of two oxygen atoms, Carbon dioxide molecule () is made up of one carbon and two oxygen atoms.
The chemical composition and chemical formula are two different things but tell us about the same thing, the kind and number of atoms a molecule is made of.
For example, chemical formula of water is and the chemical composition can be given as a 2:1 ratio of hydrogen atoms to oxygen atoms.
Nucleic acid and proteins are the two most important macromolecules. Nucleic acids (DNA, RNA) carry all the important genetic information and Proteins are required for the structure, function, and regulation of the body's different tissues and organs.
Percentage composition is the percentage of an element present in a compound. It is calculated by dividing the mass of a single element in one mole of a compound by the mass of one mole of the whole compound.