a. 2Na+ Cl2=2NaCl is the most possible chemical reaction that can occur
Answer:
Vf = 210 [m/s]
Av = 105 [m/s]
y = 2205 [m]
Explanation:
To solve this problem we must use the following formula of kinematics.

where:
Vf = final velocity [m/s]
Vo = initial velocity = 0 (released from the rest)
g = gravity acceleration = 10 [m/s²]
t = time = 21 [s]
Vf = 0 + (10*21)
Vf = 210 [m/s]
Note: The positive sign for the gravity acceleration means that the object is falling in the same direction of the gravity acceleration (downwards)
The average speed is defined as the sum of the final speed plus the initial speed divided by two. (the initial velocity is zero)
Av = (210 + 0)/2
Av = 105 [m/s]
To calculate the distance we must use the following equation of kinematics

44100 = 20*y
y = 2205 [m]
The electric field depends not on the magnetic field, but change in magnetic field. if the magnetic field is constant. electric field will be zero.
Explanation:
<h2>Speed is the rate of change of distance with time.</h2>
Answer: b. infrared
Explanation:
The visible light with the smaller frequency is associated with the color red.
While the blue is the one with the larger frequency.
Now, as the name says, infrared waves are the ones with a frequency just below the one of the red visible light.
Where the frequency of the red light is something around (4.3*10^14 Hz)
and the frequency of the infrared waves is in the range between (10^12 Hz and 10^14 Hz)
Then the correct option is b, infrared.