Explanation

Bituminous coal also called soft coal is middle-rank coal between sub-bituminous and anthracite.

Explanation

Joseph Priestley discovered laughing gas (nitrous oxide) in 1772.

It was later studied for its anesthetic properties.

Explanation

A litmus test is a phrase that originated from the use of litmus paper in chemistry, which changes color in response to certain conditions.

In a broader sense, a litmus test refers to a situation, event, or factor that clearly indicates whether a particular approach, idea, or decision is effective, valid, or acceptable.

It's a decisive test that provides clear evidence or proof.

Explanation

Straw, camphor, alcohol, petrol, diesel etc. catch fire easily to release heat energy and light energy.

So, these are examples of combustible substances.

Explanation

• The water potential of pure water is zero (0).
• It is taken as a standard reference point.
• Pure water has no dissolved solutes.
• Chemical formula: H2O
• Molar mass: 18.01528(33) g/mol
• Melting point: 0.00 °C (32.00 °F; 273.15 K) [b]
• Boiling point: 99.98 °C (211.96 °F; 373.13 K)

Last updated by NS on 20-April-2026

Explanation

Hydrogen is the lightest element, and its most common isotope (protium) has no neutrons in its atomic nucleus.

The atomic number of hydrogen is 1, which means it has one proton in its nucleus, but no neutrons.

The three main isotopes of hydrogen:

• Protium (1H): 1 proton, 0 neutrons
• Deuterium (2H or D): 1 proton, 1 neutron
• Tritium (3H or T): 1 proton, 2 neutrons

Explanation

1. Oxygen: The most abundant element in the Earth's crust, making up about 47% of the Earth's mass.
2. Silicon: The second most abundant element in the Earth's crust, making up about 27.7% of the crust 
3. Aluminum: The third most abundant element in the Earth's crust, making up around 8.1%.

Explanation

Ethyl alcohol, or ethanol, is commonly used in perfumes as a base solvent.

It helps dissolve fragrance oils and allows the scent to disperse evenly when applied.

Explanation

Temperature is a continuous variable as it does have fractional value too.

For example: Today's temperature is degree Celsius, here is not a discrete variable and hence is a continuous variable.

Explanation

Saturated hydrocarbons are called alkanes.

Alkanes are a type of hydrocarbon that have only single bonds between the carbon atoms, and are "saturated" with hydrogen atoms.

They have the general formula CnH2n+2 and are also known as paraffins.

Examples of alkanes include methane (CH4), ethane (C2H6), and propane (C3H8).