Answer:The first method to determine the chemical composition of a substance in space was using light. By determining red shift in the observed spectrum of light they could determine the elements they were observing
Explanation:
Answer:
C
Explanation:
Potassium metal reacts very rapidly with water, which forms Potassium hydroxide (KOH) and hydrogen gas (H2).
Answer : Option D) The pH of the solution is 8.0.
Explanation : pOH of a solution is a measure of hydroxide ion 
concentration in a particular solution. It gives the measure of alkalinity of a solution. Normally, aqueous solutions at 25°C have pOH which is less than 7 are usually alkaline, when pOH is found to be greater than 7 then they are acidic and when pOH will be equal to 7 then it is neutral.
pH + pOH = 14, this relationship is used to find pH of any unknown solution with given pOH value,
Here, we known pOH is 6.0, so we get,
pH = 14 - 6 = 8.0;
Hence, the pH will be 8.0.
With reference to radioactive material, half-life is the time required to 50% depletion of initial amount of material.
Given: Initial amount of radioactive material = 40 g
Half life = 4 days.
Therefore, After 4 days, amount of compound left = 40/2 = 20 g
After 8 days, i.e 2 half-life, amount of compound left = 20/2 = 10 g
Finally after 12 days, i.e. 3 half-life, amount of compound left = 10/2 = 5 g
Thus, 5 <span>grams will remain after 12 days</span>
Answer:
24 moles of oxygen are required.
Explanation:
Given data:
Number of moles of CuFeS = 12 mol
Number of moles of O₂ react = ?
Solution:
Chemical equation:
2CuFeS + 4O₂ → Cu₂S + 3SO₂ + 2FeO
now we will compare the moles of O₂ and CuFeS.
CuFeS : O₂
2 : 4
12 : 4/2×12 = 24 mol
