Answer:
c
Explanation:
Green house effect:
Temperature of atmosphere is going to increased continuously, because infrared light absorbed by gas .This increased in temperature atmosphere is called green house effect.
The green houses gases are as follows
,Carbon diaoxide,water vapor ,,Carbon diaoxide ,Methane ,,Carbon diaoxide oxide,CFCs ,ozone.
So the option c is correct.
a) Let's call x the direction parallel to the river and y the direction perpendicular to the river.
Dave's velocity of 4.0 m/s corresponds to the velocity along y (across the river), while 6.0 m/s corresponds to the velocity of the boat along x. Therefore, the drection of Dave's boat is given by:

relative to the direction of the river.
b) The distance Dave has to travel it S=360 m, along the y direction. Since the velocity along y is constant (4.0 m/s), this is a uniform motion, so the time taken to cross the river is given by

c) The boat takes 90 s in total to cross the river. The displacement along the y-direction, during this time, is 360 m. The displacement along the x-direction is

so, Dave's landing point is 540 m downstream.
d) If there were no current, Dave would still take 90 seconds to cross the river, because its velocity on the y-axis (4.0 m/s) does not change, so the problem would be solved exactly as done at point b).
Answer: 
Explanation:
Given
Initial angular speed is 
Final angular speed is 
Time period 
Magnitude of the fan's acceleration is given by

Insert the values

Thus, fan angular acceleration is 
We assume that the gas is an ideal gas so we can use the relation PV=nRT. Assuming that the temperature of the system is at ambient temperature, T = 298 K. We can calculate as follows:
PV = nRT
P = nRT / V
P = (0.801 mol ) (0.08205 L-atm / mol-K) (298.15 K) / 12 L
P = 1.633 atm