Answer:
a. because it is an element
Explanation:
its pure because it only has one type of atom, making it an element
Answer : The correct option is, (B) 273.15 K and 1 atm
Explanation :
STP : STP stands for standard temperature and pressure.
STP conditions :
The temperature is, 
or 
or 
The pressure is, 
or 
The volume is 22.4 L for 1 mole of a substance.
Hence, the correct option is, (B) 273.15 K and 1 atm
Answer:
1
all matter is made of tiny particles called atom
Answer:
6.02 × 10²³ atoms
Explanation:
The number 6.02 × 10²³ is called Avogadro number. It is the number of atoms, ions and molecules in one gram atoms of an element, one gram ions of substance and one gram molecule of a compound.
For example:
32 g of oxygen = one mole = 6.02 × 10²³ atoms O.
1.008 g of hydrogen = one mole = 6.02 × 10²³ atoms of H.
or
18 g of H₂O =one mole = 6.02 × 10²³ molecules of H₂O
44 g of CO₂ = one mole = 6.02 × 10²³ molecules of CO₂
or
62 g of NO₃⁻ = one mole of NO₃⁻ = 6.02 × 10²³ ions of NO₃⁻
