False because photosynthesis uses light energy
Answer:
Atoms form chemical bonds to make their outer electron shells more stable. The type of chemical bond maximizes the stability of the atoms that form it. Covalent bonds form when sharing atoms results in the highest stability. Other types of bonds besides ionic and covalent chemical bonds exist, too.
B. sublimation is the answer.
Answer:
Coefficient of is more than 4
Explanation:
Oxidation:
- Balance charge: ......(1)
Reduction:
- Balance Cr:
- Balance O and H in acidic medium:
- Balance charge: .......(2)
gives balanced equation:
So coefficient of is more than 4
Answer:
It takes 178.4 years to drop the activity from 15.0 Ci to 0.25 Ci
Explanation:
Step 1: Data given
Half-life time = 30.2 years
Initial activity = 15.0 Ci
Final activity = 0.250 Ci
Step 2: Calculate the time needed
N / No = e^(-0.693 * t / T1/2)
⇒ with N = The activity after dropped = 0.250 Ci
⇒ with N0 = the initial activity = 15.0
⇒ with t= the time (in years) needed to drop the activity from 15.0 to 0.250
⇒ with t1/2 = the half- life time is 30.2 years
0.250 / 15.0 = e^(-0.693 * t / 30.2)
ln(0.250/15.0) = (-0.693 * t / 30.2)
-4.09 * 30.2 = -0.693t
-123.65 = -0.693t
t= 178.4 years
It takes 178.4 years to drop the activity from 15.0 Ci to 0.25 Ci