Explanation: Only Statement A is correct. The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. Thus, helium has the largest ionization energy, while Caesium has the lowest.

Explanation: 1932. Electron – J.J. Thomson (1897). Proton – E. Rutherford. Neutron – James Chadwick (1932).

Explanation: 1913. Niels Bohr received the Nobel Prize in 1922 “for his services in the investigation of the structure of atoms and of the radiation emanating from them”.

Explanation: There are four quantum numbers: Principal (n) – It refers to the electron shell with the most electrons, giving the electron’s likely distance from the nucleus. Azimuthal (l) – It is defined as the determination of the shape of an orbital. Magnetic (m) – The subshell’s overall number of orbitals and their orientation. Spin (s) – The values of n, l, and ml have no bearing on the electron. The 4s subshell contains 1 orbital and can hold up to 2 electrons. The 4p subshell contains 3 orbitals and can hold up to 6 electrons. The 4d subshell contains 5 orbitals and can hold up to 10 electrons.The 4f subshell has 7 orbitals and can hold up to 14 electrons.

Explanation: [Ar]3d104s1 . Copper (Cu) – Atomic number (29), Electronic configuration – 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d10 or [Ar]3d104s1 .

Explanation: An electron is negatively charged particle and protons are positively charged particles.

Explanation: +1 and 0 respectively.

Explanation: As atomic number increases, subsequently mass number also increases.

Explanation: Sodium (Na) is an alkali metal. Atomic number – 11, Group – 1 and Period – 3, Sodium is a solid at room temperature. Uses – Soaps, the purification of molten metals and sodium vapour lamps.

Explanation: Avogadro number: 6.022 × 10²³. Molar mass of a substance is the mass (in grams) of one mole of the compound.

Explanation: The maximum number of electrons accommodated in a shell based on principal quantum number (n). It is represented by the formula 2n2 . K shell, n = 1, Max Electron = 2 × 1 2 = 2. L shell, n = 2, Max Electron = 2 × 2 2 = 8. M shell, n = 3, Max Electron = 2 × 3 2 = 18. N shell, n = 4, Max Electron = 2 × 42 = 32.

Explanation: According to Rutherford’s nuclear model of an atom, nucleus is very small in size as compared to the size of the atom. Rutherford explained the revolving of electrons around the nucleus, however, he did not mention how the electrons were placed inside, which ended up making Rutherford’s model an incomplete model of the atom.

Explanation: Neither I nor II. Valency – Combining power of an element. Valency of some elements : Aluminium (+3), Boron (+3), fluorine (-1).

Explanation: Crystal field theory: (1929, developed by physicist Hans Bethe) describes the breaking of orbital degeneracy in transition metal complexes due to the presence of ligands.

Explanation: London Dispersion forces. Dipole – Dipole Force is a form of intermolecular force that occurs when a polar molecule interacts with a non-polar molecule. Dipole-induced dipole force is a type of attractive force that operates between the polar molecules having permanent dipole and the molecules lacking permanent dipole.

Explanation: Nobel Prize for Chemistry (1913). Henry Taube – Nobel Prize in Chemistry (1983 – “for his studies of the mechanisms of electron transfer in metal complexes”).

Explanation: Tetra-atomic. Atomicity is the total number of atoms present in a molecule. Polyatomic (composed of three or more atoms). Phosphorus was first made by Hennig Brandt in 1669.

Explanation: Dash-wedge formula. Bond – line formula is used for every bond represented as a line in a zigzag manner.

Explanation: The electronic configuration of an element describes how electrons are distributed in its atomic orbitals. The maximum number of electrons that can be accommodated in a shell is based on the principal quantum number (n) and is represented by the formula 2n2 , where ‘n’ is the shell number.

Explanation: Compounds. John Dalton is considered the ‘Father of Modern Atomic Theory’. Dalton’s atomic theory (1808) was the first complete attempt to describe all matter in terms of atoms and their properties.

Explanation: 5 km. The radius of the atom is 10-10 m, and the radius of nucleus is 10-15 m.

Explanation: The maximum number of electrons accommodated in a shell based on principal quantum number (n). It is represented by the formula 2n2 . K shell, n = 1, Max Electron = 2 × 1 2 = 2. L shell, n = 2, Max Electron = 2 × 2 2 = 8. M shell, n = 3, Max Electron = 2 × 3 2 = 18. N shell, n = 4, Max Electron = 2 × 42 = 32.

Explanation: Na (Sodium) – It is an Alkali metal. Alkaline earth metals: Beryllium (Be, 4), Magnesium (Mg, 12), Calcium (Ca, 20), Strontium (Sr, 38), Barium (Ba, 56), Radium (Ra, 88). They have two electrons in their outermost shells. Alkali metals: Lithium (Li, 3), Sodium (Na, 11), Potassium (K, 19), Rubidium (Rb, 37), Caesium (Cs, 55), Francium (Fr, 87).

Explanation: Potassium. It makes up 2.4% by mass of the Earth crust. Aluminium is the most abundant metal and Oxygen is the most abundant non-metal found in the earth’s crust. Eight most abundant elements in the Earth’s crust are Oxygen (O), Silicon (Si), Aluminium (Al), Calcium (Ca), Iron (Fe), Magnesium (Mg), Sodium (Na), and Potassium (K).

Explanation: Bromine (Br) is the third halogen, a nonmetal in group 17 of the periodic table. Products containing bromine used in agriculture and sanitation and as fire retardants.

Explanation: Copper (Cu, Atomic no 29). It is a good conductor of heat and electricity. It is in group 11, period 4 and block ‘d’ of the periodic table. It was the first metal used by man on earth.

Explanation: 14C – It is an unstable and weakly radioactive isotope of carbon. Three Natural isotopes of carbon : 12C, 13C and 14C. Isotopes – Atoms of the same element having the same atomic number but different mass numbers. For example, take the case of hydrogen atom, it has three atomic species, namely protium ( 1 1H), deuterium ( 2 1H or D) and tritium ( 3 1H or T). The atomic number of each one is 1, but the mass number is 1, 2 and 3, respectively.

Explanation: Chromium (Cr). Tannery Wastewaters: It contains Hairs, proteins, acids, alkalis, chromium salts, sulphides, chlorides, tannins, solvents, dyes.

Explanation: Quartz (felsic mineral). Iron oxides, Al-hydroxides, clay minerals and quartz are the most stable weathered products whereas highly soluble minerals like halite are the least stable. Silicates fall within the middle range. Mafic silicates like olivine, pyroxene or amphibole breakdown relatively easily. Weathering – The breaking down or dissolving of rocks and minerals on Earth’s surface. Types of weathering: Chemical, Physical and Biological Weathering.

Explanation: Calx (calcium hydroxide). Formula – Ca(OH)2 . It is used in industrial settings, such as sewage treatment, paper production, construction, and food processing. Calum (calcium carbonate): Formula – CaCO3 .

Explanation: Element of Group 17 : The halogens are located on the left of the noble gases on the periodic table. These five toxic, non-metallic elements make up Group 17 of the periodic table and consist of : fluorine (9, F), chlorine (17, Cl), bromine (35, Br), iodine (53, I), and astatine (85, At).

Explanation: Boron, silicon, antimony. Metalloids – Chemical elements whose physical and chemical properties fall in between the metal and non-metal categories. Seven most widely recognized metalloids – Boron, germanium, silicon, antimony, arsenic, tellurium and polonium.

Explanation: Electrum. Some other alloys: Steel (Carbon and Iron). Stainless steel – (Iron with Chromium and Nickel). German silver – (copper, zinc and nickel). Rose Metal – (Bismuth , Lead and Tin). Gun Metal – (Cu + Sn + Zn + Pb). Dutch metal- (Cu and Zn). Constantan (Eureka) – Alloy of 55% Copper and 45% Nickel. Solder – It is made up of Tin and Lead.

Explanation: Carbon (C) . Atomic number – 6. Belongs to the 14th group. It is a tetravalent which makes a chemical bond with four electrons. Each form of carbon is called an allotrope. Diamond (an allotrope of carbon) is the hardest natural substance known and has a very high melting and boiling point. Graphite, another allotrope of carbon, is a conductor of electricity.

Explanation: An example of a group of isotopes is hydrogen-1 (protium), hydrogen-2 (deuterium), and hydrogen-3 (tritium). Isodiaphers – They are atoms of different elements that have the same difference between the number of protons and the number of neutrons. Example: Carbon-12 and Nitrogen-14.

Explanation: Mercury. Amalgam is an alloy of mercury with one or more metals. The most common amalgam is dental amalgam, which is used to fill cavities in teeth. Dental amalgam is a mixture of mercury, silver, tin, and copper.

Explanation: Sulphur, nitrogen. Acid Rain – When the pH of the rain water drops below 5.6, it is called acid rain. Acid rain damages buildings and other structures made of stone or metal. The main reason for this is air pollution caused by the burning of fossil fuels. The Taj Mahal has been affected by acid rain.

Explanation: Dutch Metal. Monel metal: Group of alloys of Copper and Nickel. Uses: marine engineering, chemical and hydrocarbon processing equipment, valves, pumps, shafts, fittings, fasteners, and heat exchangers, Magnalium: Mixture of magnesium and aluminium, used in making aircrafts and automobile parts, Rolled gold: An alloy of Copper and Aluminium, used for making cheap ornaments.

Explanation: Example – Fe (Iron) + H2SO4 (sulfuric acid) → FeSO4 (ferrous sulfate) + H2 (hydrogen). Non – metals react with oxygen – produce nonmetallic oxides (Acidic), Example – S (Sulphur) + O2 (Oxygen) → SO2 (Sulphur Dioxide). Metals react with oxygen – Produce metallic oxides (Basic), Example – Mg (Magnesium) + O2 (Oxygen) → MgO (Magnesium Oxide).

Explanation: Neither I nor II. Malleability – The property of metals to be beaten into thin sheets. Examples – Copper, silver. Ductility – The property of metal to be drawn into wires. Examples – Gold, silver and copper. Density and melting point of metals is high.

Explanation: Aqua regia is a mixture of hydrochloric acid and nitric acid present in the ratio 3:1. Formic acid (methanoic acid, chemical formula – HCOOH ) is the simplest carboxylic acid ,used as a preservative and antibacterial agent.

Explanation: Alkali metals have one electron in their valence shell. Group 1A of the periodic table are the alkali metals: Hydrogen (H, 1), Lithium (Li, 3), Sodium (Na, 11), Potassium (K , 19), Rubidium (Rb, 37), Cesium (Cs, 55), and Francium (Fr , 87).

Explanation: Living beings do not inhale metals during respiration. Humans get the oxygen they need by breathing through their nose and mouth into their lungs. Normal respiration rates for an adult person at rest range from 12 to 16 breaths per minute.

Explanation: odium. Reactive metals in order: Potassium (Most reactive metal), Sodium, Barium, Calcium, Magnesium, Aluminium, Zinc, Iron, Nickel, Tin, Lead, Hydrogen, Copper, Mercury, Silver, Gold, Platinum (Least Reactive).

Explanation: Physical Properties of Non metals: Poor conductors of electricity and heat, Non-malleable nor ductile, Brittle solids, May be solids, liquids, or gases at room temperature, These are not sonorous, and Transparent.

Explanation: Potassium and sodium react violently with cold water, where sodium reacts slightly stronger than Potassium. The reaction is exothermic in nature and in each reaction, hydrogen gas is given off and the metal hydroxide is produced.

Explanation: Lithium. It has the lowest density of all metals. Lithium is the first of the alkalis metals in the periodic table. It is highly reactive and does not occur freely in nature. Lithium is the only alkali metal that reacts with nitrogen.

Explanation: Water has a specific heat capacity of 4186 Jkg-1K -1 . Specific heat of some substance- Iron/Steel- 450, Copper- 390, Silver- 230, Mercury- 140, Platinum- 130, Hydrogen- 14000, Air- 718, Ice- 2100, Sea Water- 3900 etc.

Explanation: (Hg, Atomic Number-80) is also a good conductor of electricity, so it is a useful component of electrical switches. Mercury is also used in dental fillings, paints, soaps, batteries, and fluorescent lighting. It is commonly known as quicksilver and was formerly named hydrargyrum.

Explanation: The atomic number of gold is 79 and its symbol is Au, which is derived from the Anglo Saxon word. The top producers of Gold in the world are China, Australia, Russia, and the United States.