Chemical change, because the white powder heated the water and caused a thermal reaction, and possibly gas was produced due to bubbles.
Explanation:

Equilibrium constant of reaction = 
Concentration of NO = ![[NO]=\frac{2.69\times 10^{-2} mol}{1 L}=2.69\times 10^{-2} M](https://tex.z-dn.net/?f=%5BNO%5D%3D%5Cfrac%7B2.69%5Ctimes%2010%5E%7B-2%7D%20mol%7D%7B1%20L%7D%3D2.69%5Ctimes%2010%5E%7B-2%7D%20M)
Concentration of bromine gas = ![[Br_2]=\frac{3.85\times 10^{-2} mol}{1 L}=3.85\times 10^{-2} M](https://tex.z-dn.net/?f=%5BBr_2%5D%3D%5Cfrac%7B3.85%5Ctimes%2010%5E%7B-2%7D%20mol%7D%7B1%20L%7D%3D3.85%5Ctimes%2010%5E%7B-2%7D%20M)
Concentration of NOBr gas = ![[Br_2]=\frac{9.56\times 10^{-2} mol}{1 L}=9.56\times 10^{-2} M](https://tex.z-dn.net/?f=%5BBr_2%5D%3D%5Cfrac%7B9.56%5Ctimes%2010%5E%7B-2%7D%20mol%7D%7B1%20L%7D%3D9.56%5Ctimes%2010%5E%7B-2%7D%20M)
The reaction quotient is given as:
![Q=\frac{[NOBr]^2}{[NO]^2[Br_2]}=\frac{(9.56\times 10^{-2} M)^2}{(2.69\times 10^{-2} M)^2\times 3.85\times 10^{-2} M}](https://tex.z-dn.net/?f=Q%3D%5Cfrac%7B%5BNOBr%5D%5E2%7D%7B%5BNO%5D%5E2%5BBr_2%5D%7D%3D%5Cfrac%7B%289.56%5Ctimes%2010%5E%7B-2%7D%20M%29%5E2%7D%7B%282.69%5Ctimes%2010%5E%7B-2%7D%20M%29%5E2%5Ctimes%203.85%5Ctimes%2010%5E%7B-2%7D%20M%7D)


The reaction will go in backward direction in order to achieve an equilibrium state.
1. In order to reach equilibrium NOBr (g) must be produced. False
2. In order to reach equilibrium K must decrease. False
3. In order to reach equilibrium NO must be produced. True
4. Q. is less than K . False
5. The reaction is at equilibrium. No further reaction will occur. False
The first whistle is louder while the second whistle has a higher pitch
Loud vs high
Answer: 7.693 L
Explanation:
To calculate the new volume, we use the equation given by Boyle's law. This law states that pressure is directly proportional to the volume of the gas at constant temperature.
The equation given by this law is:

where,
are initial pressure and volume.
are final pressure and volume.
We are given:

Putting values in above equation, we get:

Thus new volume of the gas is 7.693 L
Answer: All of them are true