Some animals, like birds, reproduce by fusion of cells.
before a bird hatches, what protects the bird as it develops?

a. the warmth of the sunlight

b. the thin shell of the egg

c. the nutrients from its mother's body

d .the hard shell of the egg

D the hard shell of the egg

Explanation:

took the test

chemical properties are the characteristic of matter which can only be observed by changing the chemical identity of a sample like flammability reactivity and toxicity.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.