Answer:
A. + 6.
B. + 3.
Explanation:
<em>A. K₂CrO₄:</em>
- To calculate the oxidation no. of an element in a compound:
<em>We have that the sum of the oxidation no. of different elements in the compound multiplied by its no. is equal to the overall charge of the compound.</em>
∵ 2(oxidation no. of K) + (oxidation no. of Cr) + 4(oxidation no. of O) = 0.
oxidation no. of K = + 1, oxidation no. of O = - 2.
∴ 2(+ 1) + (oxidation no. of Cr) +4(- 2) = 0.
∴ 2 + (oxidation no. of Cr) - 8 = 0.
∴ (oxidation no. of Cr) - 6 = 0.
<em>∴ oxidation no. of Cr = + 6.</em>
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<em>B. Cr₂O₃:</em>
∵ 2(oxidation no. of Cr) + 3(oxidation no. of O) = 0.
oxidation no. of O = - 2.
∴ 2(oxidation no. of Cr) + 3(- 2) = 0.
∴ 2(oxidation no. of Cr) - 6 = 0.
∴ 2(oxidation no. of Cr) = + 6.
<em>∴ (oxidation no. of Cr) = + 6/2 = + 3.</em>
Hello!
The part of the carbon cycle where humans had the greatest impact is the return of CO₂ to the atmosphere by burning of ancient organic matter.
The ancient organic matter is also called Fossil Fuels. Some Fossil Fuels are Petroleum and Coal. Fossil Fuels are used to power our society and are burned to provide energy for power plants and vehicles, and by burning them, Carbon Dioxide (CO₂) is produced, increasing the natural concentration of this compound in the atmosphere.
Have a nice day!
Answer:
1.65hr
Explanation:
Given parameters:
Number of labs = 5 labs
Time taken = 3 minutes
Unknown:
Time taken in hours to grade 165 labs = ?
Solution:
Let us find the rate of the teacher;
Rate = 
Insert the parameters and solve;
Rate = 
= 1.67labs/min
Now;
Time to grade 165 labs = 
Time to grade 165 labs = 
= 98.8min
Since;
60min = 1hr
98.8min = 
= 1.65hr
