Answer:  Option D - They are too massive to be classified as planets but too small to sustain hydrogen fusion.

Explanation:

• Brown dwarfs are celestial objects that bridge the gap between the largest planets and the smallest stars.
• They possess insufficient mass to initiate sustained nuclear fusion, which is the defining characteristic of stars.
• Instead, brown dwarfs can burn a heavier form of hydrogen, but this process is limited and does not equate to the energy production seen in true stars.
• This unique position classifies them as neither full stars nor conventional planets.

Answer:  Option C - Gurdwara Bangla Sahib - Chandigarh

Explanation:

• Harmandir Sahib is located in Amritsar, while Gurdwara Janam Asthan is in Nankana Sahib, Pakistan.
• Gurdwara Bangla Sahib is in Delhi, not Chandigarh, making option C incorrect.
• Gurdwara Hazur Sahib, situated in Nanded, Maharashtra, is also accurately matched.

Answer:  Option A - Spider

Explanation:

• The newly discovered genus ‘Tenkana’ is a group of jumping spiders found in southern India, including species from Tamil Nadu, Karnataka, and other states.
• Named after the Kannada word for "south," the genus highlights the biodiversity of the region.
• The research team, comprising scientists from India and Canada, has enhanced our understanding of arachnid diversity.

Answer:  Option C - They are utilized in quantum computing and precise measurements.

Explanation:

• Rydberg atoms, which have highly excited electrons, are crucial in modern technology, particularly in quantum computing and precision measurement applications.
• Their unique properties enable the manipulation of quantum states, making them ideal for developing quantum bits (qubits) in quantum computers.
• Additionally, Rydberg atoms can enhance sensitivity in atomic clocks and magnetometers, leading to improved accuracy in various fields, including telecommunications, navigation, and fundamental physics research.

Answer:  Option A - A change in frequency due to the relative motion between the source and the observer

Explanation:

• The Doppler effect in sound occurs when the frequency (or pitch) of sound waves changes due to the relative motion between the sound source and the observer.
• If the sound source moves toward the observer, the sound waves compress, leading to a higher frequency or pitch.
• Conversely, when the source moves away, the waves stretch, resulting in a lower frequency.
• This effect is commonly experienced with passing sirens or moving vehicles.