Test : Chemistry - 2 - NDA MCQ

Transition elements containing one or more unpaired electrons show paramagnetic behavior where the effects of individual electrons are not mutually compensated. The magnetic moment due to unpaired electron spins are aligned parallel to the external magnetic field more effectively.

Large atoms have low ionization energy and low electron affinity. Therefore, they tend to lose electrons and do not tend to gain electrons. Any electrons added to a noble gas would have to be the first electron in a new (larger) energy level. This causes the noble gases to have essentially zero electron affinity.

The elements in each group have the same number of electrons in the outer orbital. Those outer electrons are also called valence electrons. They are the electrons involved in chemical bonds with other elements.

John Alexander Reina Newlands (26 November 1837 – 29 July 1898) was a British chemist. Newlands was the first person to devise a periodic table of chemical elements arranged in order of their relative atomic masses.

For oxygen, a molecule consists of two oxygen atoms, and has a weight of 2 x 16 = 32. For carbon dioxide, there is one carbon atom (weight 12) and two oxygen atoms (mass 16 x 2) for a total of 44. This means that carbon dioxide should be about 44/32 = 1.375 times (ideally) as heavy as an equivalent volume of oxygen. In reality, carbon dioxide is 1.383 times as heavy as oxygen. Even after solidification carbon dioxide is slightly heavier than similar volume of solid oxygen.

All isotopes of the same element have the same atomic number but different atomic masses.

Brass is a metallic alloy that is made of copper and zinc. Brass is commonly used for decorative purposes primarily because of its resemblance to gold. It is also a commonly used to make musical instruments due to its high workability and durability.

CaO is a chemical formula of quicklime

Ammonium (NH4+) and nitrate (NO3-) are the predominant inorganic forms of nitrogen in the soil. Plants normally use nitrogen in the form of nitrate.

When the magnesium metal burns it reacts with oxygen found in the air to form Magnesium Oxide. Oxygen and magnesium combine in a chemical reaction to form this compound. After it burns, it forms a white ash of the magnesium oxide.

Water gas is the mixture of hydrogen and carbon monoxide.  Water gas is obtained by action of steam on red-hot coke.
H2​O+C→H2​+CO