Answer:
Reducing agent - S
Explanation:
The equation for the reaction is given as;
K2Cr2O3 + H2O + S --> SO2 + KOH + Cr2O3
The balanced equation is given as:
2K2Cr2O7 + 2H2O + 3S → 3SO2 + 4KOH + 2Cr2O3
The reducing agent can be obtained by comparing the oxidation number of the elements. Increase in oxidation number signifies a reducing agent
K:
Reactant - 1
Product - 1
Cr
Reactant - +2
Product - +3
O
Reactant - -2
Product - -2
H
Reactant - +1
Product - +1
S
Reactant - O
Product - +4
S has an increase in oxidation number hence it is the reducing agent.
Although Cr has an increase in oxidation number, it occurs as a compound.
Answer:
Explanation:
We can use the formula for momentum to calculate the mass.
Half-life is the time required for decay of 50% of radio-active nuclei.
Thus, when radio-active material crosses 1st half-life, 100/2 = 50% radio-active material is left and remaining 50% is elapsed.
When, when radio-active material crosses 2nd half-life, 50/2 = 25% radio-active material is left and remaining 75% is elapsed.
When radio-active material crosses 3rd half-life, 25/2 = 12.5% radio-active material is left and remaining 87.5% is elapsed.
Thus, 2 <span>half-lives must elapse until 84 % of a radioactive sample of atoms has decayed.</span>