The answer is A ..........
Answer:
ix chemical elements that comprise Group 2 of the periodic table
Explanation:
Calcium, Magnesium, Barium, Beryllium, Strontium, and Radium are alkaline earth metals.
Answer:
The photoelectric effect occurs only for frequencies above the cutoff frequency, regardless of the intensity.
Explanation:
The photoelectric effect occurs when light is shined on metals such as zinc beyond a certain frequency (the threshold frequency), which causes electrons to escape from the zinc. The electrons which are fleeing are called photo electrons.
Therefore photo electric effect is
The photoelectric effect occurs only for frequencies above the cutoff frequency, regardless of the intensity.
im a bit confused on what the question is:(
if its just asking for the total number of km traveled it would be 21 km
The average speed of the car for the entire trip can be calculate by using:

where S is the total distance covered by the car, and t is the total time taken.
The total distance travelled by the car is:

while the total time taken is:

so, the average speed of the car is:

so, the correct answer is (3) 85 km/h.