Determine the type of chemical bond in substances, the formulas of which are: a) Ca; b) CaCl2; c) Cl2; d) HCl.

a) Ca; Metal, because it is formed by the atoms of the metal element.
b) CaCl2; Ionic, because it is formed by the atoms of the elements of metal and non-metal.
c) Cl2; Covalent non-polar, since it is formed by atoms of non-metallic elements with the same electronegativity.
d) HCl. Covalent polar, because it is formed by atoms of non-metallic elements with different electronegativity.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.