Question Library

One unique property of water is that it expands when it freezes. Most substances contract and become denser when they freeze, but water expands and becomes less dense. This is why ice floats on water.

When sodium reacts with water, it undergoes a highly exothermic reaction, producing sodium hydroxide (NaOH) and hydrogen gas (H2).

Chlorine gas exists in the gaseous state at room temperature (around 25 degrees Celsius) and standard pressure.

In a molecule with three bonding pairs and no lone pairs around the central atom, the electron pairs arrange themselves in a trigonal planar geometry, with bond angles of approximately 120 degrees.

Isotopes of an element have the same number of protons (which defines the element) but may have different numbers of neutrons. Since atoms are electrically neutral, the number of protons must equal the number of electrons in an atom.

In the electrochemical series, also known as the reactivity series, Sodium is placed at the top. The electrochemical series is a list of elements in the order of their standard electrode potentials (or redox potentials). Elements at the top of the series are more reactive and have a greater tendency to lose electrons and form positive ions.

Copper is known for its multiple oxidation states, including +1 and +2, and its compounds are used in pigments and paints to create various colors, such as blues and greens.

Filtration is commonly used to remove suspended impurities, such as dirt, sand, and other particles, from water. In this process, water is passed through a filter medium that traps the solid impurities while allowing the clean water to pass through.

The valency of an element is determined by the number of electrons it gains or loses to achieve a stable electron configuration. For an element with the electronic configuration 2, 8, 7, the outermost shell (valence shell) has 7 electrons. To achieve stability, it needs 1 more electron to fill the outermost shell, so its valency is 1.

nhydrous cobalt chloride paper is blue in the absence of water. However, when it comes into contact with water, it undergoes a color change to pink due to the formation of hydrated cobalt chloride.

Magnesium chloride is used in antacid medications to relieve heartburn and indigestion. It helps neutralize excess stomach acid.

The atomic number of an element is the number of protons in the nucleus of an atom of that element. The atomic number of aluminium is 13, which means it has 13 protons in its nucleus.

Brass is an alloy made by combining copper with zinc. It is a versatile material with a golden appearance and is used in various applications, including musical instruments, plumbing fittings, and decorative items.

When alkanoic acids react with alcohols in the presence of an acid catalyst, esterification occurs. This chemical reaction forms esters and water.

The carbonyl group (C=O) is the functional group present in alkanals. It consists of a carbon atom double-bonded to an oxygen atom.