Question

Greenhouse effect is caused by

• A. \(NO_2\)
• B. CO
• C. NO
• D. \(CO_2\)

Hint:

While many gases are present in the atmosphere, the key greenhouse gases to remember are \(H_2O\), \(CO_2\), \(CH_4\), and \(N_2O\).
Symmetrical diatomic molecules like \(N_2\) and \(O_2\) are not greenhouse gases.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The problem requires finding the hardness of water in ppm by expressing MgCl₂ as its CaCO₃ equivalent.

Step 2: Key Formula or Approach:
Convert the given salt into CaCO₃ equivalent and divide by the total mass of water in kilograms.

Step 3: Detailed Explanation:
For 19 mg of MgCl₂, the equivalent quantity of CaCO₃ is \(19\times100/95=20\) mg. This equivalent hardness distributed in 2 kg of water gives \(20/2=10\) mg/kg. Therefore, the hardness expressed in ppm is 10.

Step 4: Final Answer:
The correct hardness is 10 ppm.