Answer:
b) Phosphorus acid
Explanation:
To distinguish the type of acid of phosphorus with the oxidation state of +3, we need to be familiar with the chemical formula of each of the compounds:
Orthophosphoric acid H₃PO₄
Phosphorus acid H₃PO₃
Metaphosphoric acid HPO₃
Phyrophosphoric acid H₄P₂O₇
Now that we know the formula of the given compounds, the algebraic sum of all the oxidation numbers of all atoms in a neutral compound is zero:
Only phosphorus acid yielded an oxidation state of +3 for phosphorus in the compound.
H₃PO₃:
we know the oxidation state of H = +1
O = -2
The oxidation state of P is unknown. We can express this as an equation:
3(+1) + P + 3(-2) = 0
3 + P -6 = 0
P-3 = 0
P = +3
Radioactive material obeys 1st order decay kinetics,
For 1st order reaction, we have
k =

where, k = rate constant of reaction
Given: Initial conc. 100, Final conc. = 6.25, t = 18.9 hours
∴ k =

= 0.1467 hours^(-1)
Now, for 1st order reactions: half life =

= 4.723 hours.
The cell notation is:

here in cell notation the left side represent the anodic half cell where right side represents the cathodic half cell
in anodic half cell : oxidation takes place [loss of electrons]
in cathodic half cell: reduction takes place [gain of electrons]
1) this is a galvanic cell
2) the standard potential of cell will be obtained by subtracting the standard reduction potential of anode from cathode


Therefore

3) as the value of emf is positive the reaction will be spontaneous as the free energy change of reaction will be negative
Δ
As reaction is spontaneous and there will be conversion of chemical energy to electrical energy it is a galvanic cell.
The most viscous among the choices is D. Honey at room temperature.
Viscosities of liquids typically vary with temperature. The higher the temperature, the lower the viscosity. Among the choices, only motor oil and honey appear to be the most viscous. The clue that helps determined the answer are the words "hot" and "room temperature". Hot motor oil is less viscous, while honey at room temperature is more viscous. Even comparing their viscosities at room temperature, honey already has a higher viscosity than motor oil.
Answer is: A) Sr (strontium).
The reactivity series<span> is a series of metals from highest to lowest reactivity.</span><span> Metal higher in the reactivity series will displace another.
</span>Strontium is only higher in this group from magnesium. Strontium is stronger reducing agent than magnesium, gives electrons easier.