Q1: Which is the only metal that exists in liquid state at room temperature?

ANS:B - Mercury

It seems you've mentioned "Mercury." Mercury is a chemical element with the symbol Hg and atomic number 80. Here's some information about it:

1. Physical Properties: Mercury is the only metallic element that is liquid at standard conditions for temperature and pressure. It has a silvery-white appearance and is known for its high density, low melting point, and high surface tension.
2. Toxicity: Mercury is highly toxic to humans and animals, primarily affecting the nervous system. Exposure to mercury can occur through inhalation of vapors, ingestion of contaminated food or water, or contact with mercury-containing products. Due to its toxicity, the use of mercury in various products and processes has been significantly restricted in many countries.
3. Uses:
   • Historically, mercury was used in various applications such as thermometers, barometers, and fluorescent lamps due to its unique physical properties.
   • It was also used in dental amalgam fillings, although its use in this application has decreased due to health concerns.
   • Mercury was once widely used in industrial processes such as gold mining and chlor-alkali production. However, many of these uses have been phased out or reduced due to environmental and health concerns.
4. Environmental Impact: Mercury pollution is a significant environmental problem. When released into the environment, mercury can bioaccumulate in the food chain, leading to harmful effects on ecosystems and human health. Contaminated water bodies can also pose risks to aquatic life and human populations.
5. Regulation: Due to its toxicity and environmental impact, the use, handling, and disposal of mercury are regulated by various governmental and international agencies. Efforts are underway to reduce mercury emissions and phase out the use of mercury in products and processes where feasible.