Tag: science & technology

To answer this question, the user needs to know about the different types of substances and their properties.

The correct answer is C. Solid carbon dioxide.

Explanation for each option:

A. Liquid nitrogen: This option is incorrect. Liquid nitrogen is a colorless, odorless, and tasteless liquid that is commonly used as a refrigerant. It is not dry ice.

B. Water ice: This option is incorrect. Water ice is a frozen form of water. Although it is a solid, it is not dry ice.

C. Solid carbon dioxide: This option is correct. Dry ice is the solid form of carbon dioxide, which is a gas at room temperature. It gets its name because it does not melt into a liquid, but rather sublimates directly into a gas.

D. Frozen ethanol: This option is incorrect. Ethanol is a clear, colorless liquid that freezes at a temperature of -114 degrees Celsius. Although it is a solid at very low temperatures, it is not dry ice.

Therefore, the correct answer is C. Solid carbon dioxide.

Hydrogen has the highest calorific value (about 141,790 kJ/kg) among the options. Coal (~24,000-30,000 kJ/kg), wood (~15,000-19,000 kJ/kg), and rubber have much lower calorific values. Hydrogen's high energy content per unit mass makes it the fuel with the greatest heating value.

Hafnium (Hf, atomic number 72) is named after Copenhagen, Denmark - 'Hafnia' is the Latin name for Copenhagen. Arsenic, Cobalt, and Copper are not named after Danish cities. Hafnium was discovered in 1923 by Coster and Hevesy in Copenhagen.

Radon (Rn, atomic number 86) is the heaviest naturally occurring noble gas with atomic mass 222. Xenon (131), Argon (40), and Helium (4) are all lighter. Radon is radioactive and occurs naturally from uranium decay, making it the heaviest in the noble gas group.

The Perseids meteor shower is also called 'Tears of Saint Lawrence' because it peaks around August 10th, the feast day of Saint Lawrence. Saint Elmo's Fire is a weather phenomenon, while Northern/Southern Lights refer to auroras. The Perseids occur annually when Earth passes through debris from Comet Swift-Tuttle.

Leo Hendrik Baekeland, a Belgian chemist, invented Bakelite in 1907. It was the first synthetic thermosetting plastic. Charles Goodyear worked with rubber vulcanization, Roy Plunkett discovered Teflon, and Henry Ford developed automobile assembly lines - none invented Bakelite.

The Moon's diameter is about 27% of Earth's diameter. If Earth is 6 inches, the Moon would be about 1.6 inches - roughly golf ball sized. A tennis ball is ~2.7 inches, ping pong ball is ~1.6 inches but much lighter, and baseball is ~2.9 inches. Golf ball best represents both size and relative massiveness.

To solve this question, the user needs to have knowledge about the colors of different gases.

Option A: Chlorine is a greenish-yellow gas at room temperature and pressure. Therefore, option A is a possible correct answer.

Option B: Hydrogen is a colorless gas at room temperature and pressure. Therefore, option B is incorrect.

Option C: Krypton is a colorless gas at room temperature and pressure. Therefore, option C is incorrect.

Option D: Neon is a colorless gas at room temperature and pressure. Therefore, option D is incorrect.

The Answer is: A

The National Geophysical Research Institute (NGRI), under the Council of Scientific and Industrial Research (CSIR), is located in Hyderabad, India. It is a premier research institute in Earth Sciences. The other cities (New Delhi, Kolkata, Mumbai) host other CSIR institutes but not NGRI.

Pure water freezes at 32°F (0°C) at standard atmospheric pressure. This is the standard freezing point of water. The other temperatures (47°F, 0°F, 19°F) are incorrect - 0°F is very cold (~-18°C), and 47°F and 19°F are above freezing.