Answer is (2) - hydrogen carbonate
<em>Explanation:</em>
NaHCO₃ is an ionic compound which is made from Na⁺ and HCO₃⁻ ions. The decomposition is
NaHCO₃ → Na⁺ + HCO₃⁻
Among the resulted ions, Na⁺ is a monatomic ion while HCO₃⁻ is a polyatomic ion.
<em>Polyatomic ions mean ions which are made of two or more different atoms.</em>
HCO₃⁻ is made from 3 atoms as H, C and O. The name of HCO₃⁻ ion is bicarbonate or hydrogen carbonate.
Answer:

Explanation:
Mass of one tablet = 20 mg
Mass of two tablets = 
Percent that is soluble in water = 40%
Mass of tablet that is soluble in water = 
So, mass of solute is 
Density of water = 1 kg/L
Volume of water = 1 L
So, mass of 1 L of water is 
PPM is given by

Hence, the concentration of iodine in the treated water
.
Answer:
Heat lost to the surroundings
Heat lost to the thermometer
Explanation:
All changes in heat, or energy, can be explained. Many of the reactions or changes we see in the world involve the conversion of energy. For example as we heat up a substance (eg. water), the amount of energy we put in should give us an exact temperature. However, this is a "perfect world" scenario, and does not occur in real life. Whenever heat is added to a substance like water, we always need to account for the energy that is going to be lost. For example, heat lost to evaporation or even the effect of measuring the temperature with a thermometer (the introduction of anything including a thermometer will affect the temperature).
Answer:
Equilibrium constant for
is 0.5
Equilibrium constant for decomposition of
is 
Explanation:
dissociates as follows:

initial 0.72 mol 0 0
at eq. 0.72 - 0.40 0.40 0.40
Expression for the equilibrium constant is as follows:
![k=\frac{[PCl_3][Cl_2]}{[PCl_5]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B%5BPCl_3%5D%5BCl_2%5D%7D%7B%5BPCl_5%5D%7D)
Substitute the values in the above formula to calculate equilibrium constant as follows:
![k=\frac{[0.40/1][0.40/1]}{0.32/1} \\=\frac{0.40 \times 0.40}{0.32} \\=0.5](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B%5B0.40%2F1%5D%5B0.40%2F1%5D%7D%7B0.32%2F1%7D%20%5C%5C%3D%5Cfrac%7B0.40%20%5Ctimes%200.40%7D%7B0.32%7D%20%5C%5C%3D0.5)
Therefore, equilibrium constant for
is 0.5
Now calculate the equilibrium constant for decomposition of 
It is given that
is decomposed.
decomposes as follows:

initial 1.0 M 0 0
at eq. concentration of
is:
![[NO_2]_{eq}=1-(0.000066) = 0.999934\ M](https://tex.z-dn.net/?f=%5BNO_2%5D_%7Beq%7D%3D1-%280.000066%29%20%3D%200.999934%5C%20M)
![[NO]_{eq}=6.6 \times 10^{-5}\ M](https://tex.z-dn.net/?f=%5BNO%5D_%7Beq%7D%3D6.6%20%5Ctimes%2010%5E%7B-5%7D%5C%20M)
Expression for equilibrium constant is as follows:
![K=\frac{[NO]^2[O_2]}{[NO_2]^2}](https://tex.z-dn.net/?f=K%3D%5Cfrac%7B%5BNO%5D%5E2%5BO_2%5D%7D%7B%5BNO_2%5D%5E2%7D)
Substitute the values in the above expression
![K=\frac{[6.6\times 10^{-5}]^2[3.3 \times 10^{-5}]}{[0.999934]^2} \\=1.79\times 10^{-14}](https://tex.z-dn.net/?f=K%3D%5Cfrac%7B%5B6.6%5Ctimes%2010%5E%7B-5%7D%5D%5E2%5B3.3%20%5Ctimes%2010%5E%7B-5%7D%5D%7D%7B%5B0.999934%5D%5E2%7D%20%5C%5C%3D1.79%5Ctimes%2010%5E%7B-14%7D)
Equilibrium constant for decomposition of
is 
Answer:
Nickle
Explanation:
In statement it is given that the metal "M" has a formula "MCl₂" which means it has a charge of +2 as each Chlorine atom has -1 charge. Therefore, it is cleared that this metal has lost 2 electrons and originally it was carrying 28 electrons.
After that periodic table is concerned and a metal with 28 atomic number was tracked because a neutral atom with 28 electrons must have 28 protons and protons are infact the atomic number.
Hence, in periodic table the metal with 28 atomic number is found to be Nickle.