Question

Please help with both

Answer 1

Answer:

D =Average atomic mass  = 10.801 amu.

5) True

Explanation:

Abundance of B¹⁰= 19.9%

Abundance of B¹¹ = 80.1%

Atomic mass of B¹⁰ = 10 amu

Atomic mass of B¹¹ = 11 amu

Average atomic mass = ?

Solution:

Average atomic mass  = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass  = (10×19.9)+(11×80.1) /100

Average atomic mass =  199 + 881.1 / 100

Average atomic mass  = 1080.1 / 100

Average atomic mass  = 10.801 amu.

2)A chemical reaction is one in which a new elements is created

True

False

Answer:

In chemical reaction new substances are created.

For example:

Photosynthesis:

It is the process in which in the presence of sun light and chlorophyll by using carbon dioxide and water plants produce the oxygen and glucose.

Carbon dioxide + water + energy →   glucose + oxygen

water is supplied through the roots, carbon dioxide collected through stomata and sun light is capture  by chloroplast.

Chemical equation:

6H₂O + 6CO₂ + energy  →   C₆H₁₂O₆ + 6O₂

it is known from balanced chemical equation that 6 moles of carbon dioxide react with the six moles of water and created one mole of glucose and six mole of oxygen.