1. Which of these is a useful Chemical reaction?  a) Food rancidity

b) Photosynthesis

c) Rusting

d) None

2. Which of the following statements is True?

a) Respiration is chemically the opposite of photosynthesis

b) Rusting is a rapid process

c) Complete combustion requires short supply of oxygen

d) Photosynthesis requires oxygen

Help me please, no guess work.
THANKS!.

1. b

2.a

Explanation:

Photosynthesis is a useful reaction because it provides plants with food Rusting has disadvantages

Rusting is a slow process... complete combustion requires a lot of oxygen... photosynthesis requires carbon(IV) oxide and not oxygen

so she was walking and she stepped on warm jeffy , uh uh uhh dadye i just pooped my pants

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally