Conductance

Step 1: Concept
Resistance . When stretched, volume remains constant.
Step 2: Analysis
If , then to keep volume constant. .
Step 3: Conclusion
The new resistance is .
Final Answer: (C)

Step 1: Test Principle
The chromyl chloride test is used for the qualitative detection of chloride ( ) ions.
Step 2: Observations
Heating a chloride salt with and conc. produces reddish-brown vapours of chromyl chloride ( ). Passing these into and adding lead acetate forms a yellow precipitate of lead chromate ( ).
Step 3: Identification of Error
During this reaction, chlorine gas ( ) is not liberated.
Final Answer: (d)

Step 1: Understanding the formula for resistance change with temperature.
The resistance of a material changes with temperature according to the formula: where: - is the resistance at temperature , - is the resistance at 0°C, - is the temperature coefficient of resistance, and - is the temperature in °C.

Step 2: Set up the equation.
We are asked to find the temperature at which the resistance is three times its value at 0°C. Hence, we set: Substitute this into the formula for : Simplifying:

Step 3: Solve for temperature.
Now, substitute the given value for :

Step 4: Conclusion.
The temperature at which the resistance becomes three times its value at 0°C is , which is option (3).

Step 1: Understanding the Concept:
For SHM, , so . Also . Thus .
Step 2: Detailed Explanation:
, . Total force .
But . So .
Hz.
Step 3: Final Answer:
Thus, frequency = 10 Hz.

Concept: When stretched, volume remains constant:

Step 1: New length.


Step 2: New area using volume conservation.


Step 3: New resistance.