Dual Nature Of Matter

Step 1: Photons are electromagnetic waves and always travel with the speed of light in vacuum.
Step 2: The speed of light does not depend on wavelength or frequency. Hence, photons of wavelengths and travel with the same velocity.
Step 3: Therefore, the ratio of their velocities is:

Step 1: Energy of one photon Take J·s, m/s, \AA\ = m.
Step 2: Total energy from bulb
Step 3: Number of photons
Step 4: Closest option (D).

Step 1: Volume of hydrogen produced per second At STP, mole of gas occupies . Step 2: Calculate moles of hydrogen produced per second Step 3: Electrochemical relation for hydrogen evolution For the reaction: moles of electrons (i.e., charge) are required to produce mole of hydrogen gas. Step 4: Calculate current required Charge required per second: Hence, the required current is .

We use the definition .
Given .
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We use the approximation .
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The exact value is , which is closest to 2.5.