General Knowledge: Indian Geography, English Grammar, and Environment

The correct idiomatic expression is 'at risk' when something is in danger or exposed to harm. The investment is in danger, so 'at risk' is the proper preposition choice. 'In risk' is not standard English, and 'to risk' or 'from risk' don't fit this context.

The correct expression is 'at least' when indicating a minimum amount or duration. 'Waited at least a half an hour' means waited for a minimum of 30 minutes. 'From least,' 'by least,' and 'until least' are not standard English expressions in this context.

Earth Day is indeed celebrated across the world (April 22) to inspire awareness and appreciation for our planet's environment. Despite the spelling errors in the question ('accross' instead of 'across,' 'approciation' instead of 'appreciation'), the factual statement is true.

When using the future perfect tense ('would have finished') with a time reference, 'by' is the correct preposition. 'By then' means 'by that time' - indicating completion before or at that specific future moment. 'Until then,' 'to then,' and 'at then' are not correct with the future perfect construction.

The correct idiomatic expression is 'from personal experience' when stating something based on one's own experience. The phrase 'from personal experience, you're going to have to...' properly introduces advice based on the speaker's experience. 'At,' 'of,' and 'in' are not the correct prepositions for this expression.

Plastic is largely non-biodegradable and does not decompose naturally like organic matter. It requires high-energy processes like UV radiation to slowly break down into smaller particles, which can take hundreds of years.

Tobacco smoke contains fine particulate matter (PM2.5) that directly enters and damages the respiratory system. The lungs are the primary organs exposed to inhaled smoke, making them most vulnerable to cancer, COPD, and other diseases.

Delhi is the capital of the National Capital Territory of Delhi. As the name indicates, this union territory's capital is Delhi itself, which is also the national capital of India.

Chandigarh is a union territory that also serves as the capital of both Punjab and Haryana states. The capital of Chandigarh UT is Chandigarh itself, making option A correct.

Sacramento is the capital city of California. While Los Angeles and San Francisco are more famous, Sacramento has been the state capital since 1854 and houses the California State Capitol building.