18. <span>Answer is </span>
A<span>
<span>Since the enthalpy of reaction is positive, the
forward reaction is<span> an endothermic reaction which means the energy
is gained from the surrounding to happen the reaction. If the temperature
decreases, according to the </span></span>Le Chatelier's principle, the system tries to become equilibrium
by increasing temperature. Since forward reaction is endothermic (because of
the bond breaking), the backward reaction is exothermic (because of the bond
making) which releases the energy to the surroundings. This makes the increase
of temperature. So if the backward reaction is promoted because of the decrease
of temperature, then the concentration of H</span><span>₂ will decrease.</span>
<span>
</span>
19. Answer is A.
The reactant side
has 2 moles/molecules of reactants and the product side has 4 moles/molecules
of products which come from 1 N₂(g) and 3 H₂<span>(g). If the pressure is reduced in the system, according to the Le Chatelier's principle, the
system tries to increase the pressure. </span><span>Hence, forward
reaction is promoted because of the higher number
of molecules in product side. If the forward reaction is promoted, the
concentration of NH</span>₃(g) will decreased.
<span>20. </span>Answer is C.
If the concentration
of reactant is increased in the
system, according to the Le Chatelier's principle, the system tries
to reduce the concentration of that reactant. So if NH₃(g) concentration
is increased, then to be equilibrium, the forward reaction will be promoted.
Then the concentration of N₂<span>(g) will increase.</span>
<span> </span>
Answer:
The force of gravity acting on the car is <u>9800 N vertically downward.</u>
Explanation:
Given:
Mass of the car given is 1000 kg.
We know that the force of gravity is the force applied by the center of Earth on any body. The force of gravity is also called the weight of the body and always act towards the center of the Earth.
From Newton's second law, we know that the force acting on a body is equal to its mass and acceleration.
Here, the acceleration acting on the car is due to gravity and thus has a constant value of 9.8 m/s² on the surface of Earth.
Therefore, the force of gravity acting on the car is given using the Newton's second law as:
Force of gravity = Mass of car 
Acceleration due to gravity.
Force of gravity = (1000 kg) (9.8 m/s²)
Force of gravity = 9800 N [1 kg.m/s² = 1 N]
Therefore, the force of gravity acting on the car is 9800 N vertically downward.
Answer:
In this conditions, the gaswll weight 46.74 g.
Explanation:
The idal gas law states that:
PV = nRT,
P: pressure = 740 mmHg = 0.97 atm
V: volume = 14.5 L
n: number of moles
R: gas constant =0.08205 L.atm/mol.K
T: temperature = 29°C = 302.15K
1 mol gas ___ 82 g
0.57 mol gas __ x
x = 46.74 g
Answer:
A} Kinetic chemical energy
Explanation:
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