Question

The monomer involved in the formation of polystyrene is

• A. \(CH_2=CH-Cl\)
• B. \(CH_2=CH-CN\)
• C. \(CH_2=CH-C_6H_5\)
• D. \(CH_2=CH-CH_3\)

Hint:

Many common polymer names are simply the prefix "poly-" added to the name of the monomer.
For example: poly(ethene), poly(propene), poly(styrene), poly(vinyl chloride).
Recognizing this naming convention can help you quickly identify the monomer.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks us to compute the hardness of water caused by MgCl₂ in ppm.

Step 2: Key Formula or Approach:
Express the dissolved MgCl₂ as CaCO₃ equivalent and divide by the sample mass in kilograms.

Step 3: Detailed Explanation:
The given 19 mg of MgCl₂ corresponds to \(19\times100/95=20\) mg of CaCO₃. Since this amount is present in 2 kg of water, hardness is \(20/2=10\) mg/kg, which is equivalent to 10 ppm.

Step 4: Final Answer:
The hardness of the water is 10 ppm.