प्रकाश तरंगों का प्रकाशीय प्रभाव (Optical effect) मुख्य रूप से किसके कारण होता है?

The arrival of which commission in India triggered widespread protests, including mass hartals across the country in 1928?

Which of the following leaders was instrumental in initiating and leading India’s struggle for independence?

Which of the following viceroys of India is associated with the 'Ilbert Bill' controversy?