Practice MCQ Questions and answers on Chemistry-GK

Liquid hydrogen and liquid oxygen are used as propellent for rocket.

Hydrogenation - to treat with hydrogen - is a chemical reaction between molecular hydrogen (H₂) and another compound or element, usually in the presence of a catalyst. The largest scale application of hydrogenation is for the processing of vegetable oils (fats to give margarine and related spreads and shortenings). Typical vegetable oils are derived from polyunsaturated fatty acids (containing more than one carbon-carbon double bonds). Their partial hydrogenation reduces most but not all, of these carbon-carbon double bonds.

Hydrogen gas(H₂) will effuse out of football bladder most quickly.

The property of hydrogen which distinguishes it from alkali metals is that hydrogen is a non - metal while all other members of group 1( alkali metals ) are metals.

Hydrogen is a chemical element with symbol H and atomic number 1. With an average atomic weight of 1.00794 u (1.007825 u for hydrogen-1), hydrogen is the lightest element and its monatomic form (H₁) is the most abundant chemical substance, constituting roughly 75% of the Universe’s baryonic mass. Nonremnant stars are mainly composed of hydrogen in its plasma state. Air is the name given to the atmosphere used in breathing and photosynthesis. Dry air contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%. Naturally occurring atomic hydrogen is rare on Earth because hydrogen readily forms covalent compounds with most elements and is present in the water molecule and in most organic compounds.

At standard temperature and pressure, hydrogen is a colourless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic gas with the molecular formula H₂. Naturally occurring atomic hydrogen is rare on Earth because hydrogen readily forms covalent compounds with most elements and is present in the water molecule and in most organic compounds. Hydrogen plays a particularly important role in acid-base chemistry with many reactions exchanging protons between soluble molecules. Hydrogen gas (dihydrogen or molecular hydrogen) is highly flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion for hydrogen is 286 kJ/mol. Pure hydrogen-oxygen flames emit ultraviolet light and are nearly invisible to the naked eye, as illustrated by the faint plume of the Space Shuttle Main Engine compared to the highly visible plume of a Space Shuttle Solid Rocket Booster.

In a flame of pure hydrogen gas, burning in air, the hydrogen (H₂) reacts with oxygen (O₂) to form water (H₂O) and releases heat.

Liquid hydrogen (LH₂) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H₂ form. To exist as a liquid, H₂ must be cooled below hydrogen’s critical point of 33 K. However, for hydrogen to be in a full liquid state without evaporating at atmospheric pressure, it needs to be cooled to 20.28 K (-423.17 °F/-252.87°C). One common method of obtaining liquid hydrogen involves a compressor resembling a jet engine in both appearance and principle. Liquid hydrogen is typically used as a concentrated form of hydrogen storage

Hydrogen gas is used in the manufacture of Vanaspati Ghee.

Cadmium does not react with water to produce hydrogen.