Explanation: A. Aufbau principle states that 'in the ground state of the atom, the orbitals are filled in order of their increasing energies, starting with the orbital of lowest energy.' The word aufbau is German word which means building up. The increasing order of energy and hence that of filling of orbitals is as follows: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p.

Explanation: C. As it is given that half life of given substance is 4 months. The amount of substance left after 4 months =

Explanation: D. Zirconium is non-radioactive substance as the substance which have atomic number above 80 shows radioactivity. The rest three Astatine, Francium and Tritium are radioactive in nature. There are five naturally occurring isotopes of Zirconium: Zirconium- 90, Zirconium-91, Zirconium-92, Zirconium-94 and Zirconium-96. Natural Zirconium has two radioactive isotopes 94Zr & 96Zr. Three stable isotopes of Zirconium also found in nature, which account for 79.82% of the total amount.

1. A. Zero mass 1. Positron
2. B. Fractional charge 2. Neutrino
3. C. Fractional spin 3. Quark
4. D. Integral spin 4. Photon

Codes:

Explanation: A. The Standard Model of particle physics assumed that neutrino are massless. A quark is an elementary particle and a fundamental constituent of matter. Quarks have fractional electric charge values either

Explanation: C. Aqueous solution of copper sulphate is acidic in nature because copper sulphate on dissolving with water, following chemical reaction takes place. CuSO4(s) + 2H2O ? Cu(OH)2(l) + H2SO4(aq). Now as we can see in above chemical equation the sulphuric acid generated is strong mineral acid which results into increase in acidity of solution. Thus aqueous solution of copper sulphate is acidic in nature.

1. Ionisation potential gradually decreases along a period.
2. In a group of elements, electron affinity decreases as the atomic weight increases.
3. In a given period, electro-negativity decreases as the atomic number increases.

Which of these statement (s) is/are correct?

Explanation: B. The electron affinity of a molecule or atom is the energy change when an electron is added to the neutral atom to form a negative ion. This property can only be measured in an atom in gaseous state. X + e

Explanation: A. As molecular weight increases with increase in the length of carbon-carbon chain.

1. Ionic compounds are insoluble in alcohol.
2. Ionic compounds in the solid state are good conductor of electricity.

Which of these statements is/are correct?

Explanation: A. Ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Following the aphorism, "like dissolves like", ionic compounds dissolve in polar solvents, especially those that ionize, such as water and ionic liquids. They are usually appreciably soluble in other polar solvents such as alcohols, acetone. Solid ionic compounds cannot conduct electricity because there are no mobile ions or electrons present in the lattice.

Explanation: A. Magnetic quantum number represents the number of orbitals present in the sub-shell magnetic quantum number about the orientation of the orbital.

Explanation: A. Liquid sodium is used as a coolant because water is difficult to use as a coolant for a fast reactor because water acts as a neutron moderator that slows the fast neutrons into thermal neutrons. While it may be possible to use supercritical water as a coolant in a fast reactor, this would require a very high pressure. In contrast, sodium atoms are much heavier than both the oxygen and hydrogen atoms found in water, and therefore the neutrons lose less energy in collisions with sodium atoms. Sodium also need not be pressurized since its boiling point is higher than the reactor's operating temperature. A disadvantage of sodium is its chemical reactivity, which requires special precautions to prevent and suppress fires. If sodium comes into contact with water it explodes, and it burns when in contact with air.

1. to keep the washing powder dry.
2. to maintain the alkalinity of the powder.

Which of these statements is/are correct?

Explanation: C. The addition of silicates to synthetic detergents has proved very beneficial. Silicates soften water by the formation of precipitates that can be easily rinsed away. Soluble silicates contribute to detergents as cleaning aids, processing aids, and corrosion inhibitors. As cleaning aids, soluble silicates provide alkalinity and promote soil suspension. Sodium sulphate is simply a filler in detergent powder, in much the same way as fillers are used in many medical tablets, it doesn't play any active role as such.

Explanation: C. During the photochemical smog ozone, nitric acid, PAN are produced.

Explanation: C. Creating firework colors is a complex endeavor, requiring considerable art and application of physical science. Strontium and barium both are alkaline earth metal and are extremely reactive. They both impart characteristic color to flame. Strontium salts impart a red color to fireworks. Strontium compounds are also important for stabilizing fireworks mixtures. Barium is used to create green colors in fireworks, and it can also help stabilize other volatile elements

1. A. CNG 1. Carbon monoxide, Hydrogen
2. B. Coal gas 2. Butane, Propane
3. C. LPG 3. Methane, Ethane
4. D. Water gas 4. Hydrogen, Methane, Carbon monoxide

Codes:

Explanation: B. Compressed natural gas (CNG) is made by compressing natural gas which is composed of methane (CH4), it also contain small amount of ethane. Coal gas typically contains hydrogen, methane and carbon monoxide. LPG is the abbreviation or short form of Liquefied Petroleum gas. The major constituents of LPG is propane and butane. Water gas is a synthesis gas, containing carbon monoxide and hydrogen.

1. Caffeine, a constituent of tea and coffee is a diuretic.
2. Citric acid is used in soft drinks.
3. Ascorbic acid is essential for formation of bones and teeth.
4. Citric acid is a good substitution ascorbic acid in our nutrition.

Which of the statements given above are correct?

Explanation: D. Caffeine also spelled caffei is most commonly consumed by humans in infusions extracted from the bean of the coffee plant and the leaves of the tea bush, as well as from various foods and drinks containing products derived from the kola nut. Acids are added to soft drinks for extra bite and mouth feel. The primary acid used in colas is phosphoric acid, while the one used in citrus flavoured drinks is usually citric acid. Citric acid is a good substitution of ascorbic acid as per nutritional value.

Explanation: B. Solder is a fusible metal alloy with a melting point or melting range of 90 to 450 degree Celsius (190 to 840

1. Benzene
2. Carbon tetrachloride
3. Sodium carbonate
4. Trichloroethylene

Which of the above/is are used as dry cleaning chemical?

Explanation: C. Dry cleaning is a cleaning process for clothing and textiles involves using a chemical solvents other then water. The solvent used is typically trichloroethylene while carbon tetra chloride and tri chloro-ethane is used historically. Benzene is other common agent used for this purpose.

1. Ilmenite
2. Zirecon
3. Sillimanite
4. Tungsten

Select the correct answer using the codes given below:

Explanation: B. Ilmenite, Zirecon and Sillimanite are found in kollam district in Kerala but tungsten is not found in the beach sands of Kerala.

Explanation: D. Crookes glass is a type of glass that contains cerium and other rare earths and has a high absorption of ultraviolet radiation used in sunglasses.

Explanation: B. Selenium.

Explanation: C. Philosopher's wool is a oxide of zinc a white powder used as a pigment, cosmetics, glass, inks and in zinc ointment.

Explanation: B. German silver has a color resembling silver, but is an alloy of primarily copper, nickel and zinc. Chlorargyrite is the mineral form of silver chloride (AgCl). It is also known as horn silver. Proustite is a sulfosalt mineral consisting of silver sulfarsenide, Ag3AsS3, known also as light red silver or ruby silver ore, and an important source of the metal. Silver nitrate is an inorganic compound with chemical formula AgNO3. It was once called lunar caustic because silver was called luna by the ancient alchemists.

Explanation: D. RDX, an initialism for Research Department Explosive, is an explosive nitroamine widely used in military and industrial applications. It is also known less commonly as cyclonite. Its chemical name is cyclotrimethylene trinitramine.

Explanation: C. Xenon is called the 'stranger' gas. This gas very un-reactive and heavier than air, that was why named strange (in greek it means 'xenon').

Explanation: B. The lightest metal in the periodic table is lithium (Li) with atomic number 3 density 0.53 kg/L. Lithium metal is extremely soft (and highly reactive) and so is unusable for many applications. Osmium is a hard metallic element which has the greatest density of all known elements. It is twice as heavy as lead, and has a specific gravity of 22.59.

Explanation: C. Bisphenol A, commonly abbreviated as BPA, is an organic compound with two phenol functional groups. Bisphenol A is used primarily to make plastics which is used in making food packaging material. It is a key monomer in production of epoxy resins and used to make polycarbonate plastic. Polycarbonate plastic, which is clear and nearly shatter-proof, is used to make a variety of common products including baby and water bottles, sports equipment, medical and dental devices, dental fillings and sealants, eyeglass lenses, CDs and DVDs, and household electronics.

Explanation: C. Cause of blast in a mine in generally mixture of methane and air. CH4 in the main gas exerted from a mine, when it comes in contact with air, explosions take place.

Explanation: A. A dry cell has the electrolyte immobilized as a paste, with only enough moisture in the paste to allow current to flow. The electrolyte is ammonium chloride in the form of a paste next to the zinc anode. In some more modern types of so called 'high power' batteries, the ammonium chloride has been replaced by zinc chloride.

Explanation: D. Nitroglycerine (NG) also known as nitroglycerine, trinitroglycerin, trinitroglycerine, 1,2,3 tri nitroxypropane and glyceryl trinitrate is a heavy, colorless, oily, explosive liquid obtained by nitrating glycerol. Alfred Nobel discovered that mixing nitroglycerin with diatomaceous earth would turn the liquid into a paste, called dynamite. An advantage of dynamite was that it could be cylinder-shaped for insertion into the drilling holes used for mining.

1. A. 2 1. Oxidation number of Mn inMnO2
2. B. 3 2. Oxidation number of S in H2S2O7
3. C. 4 3. Oxidation number of Ca in CaO
4. D. 6 4. Oxidation number of Al in NaAlH4

Codes:

Explanation: A. The oxidation number characterises the oxidation state of an element in a compound. It is a full number, positive or negative, which indicates the amount of electron loss or gain by this element in the given compound, with respect to the neutral atom. Oxidation number of calcium is 2 in calcium oxide (CaO). Oxidation number of Aluminium is +3 in Sodium aluminium hydride (NaAlH4) is a chemical compound used as a reducing agent. Oxidation number of manganese is 4 in Manganese dioxide (MnO2). Oxidation number of sulphur is 6 in Pyrosulfuric Acid (H2S2O7).

Explanation: A. Synthetic detergents are sodium salt of long chain sulphonic acid or alkyl hydrogen sulphate. Hardness in water is due to presence of chlorides, sulphates and nitrates salts of calcium and magnesium. Now detergents are capable of forming soluble salts even with the calcium and magnesium ions present in hard water and forms lather easily in hard water.

Explanation: C. hydrogen vehicle is an alternative fuel vehicle that uses hydrogen as its onboard fuel for motive power. The hydrogen vehicle use hydrogen fuel cell for generation of motive power. These fuel cell in which hydrogen serve as a fuel and oxygen as an oxidant emits exhaust of water.

Explanation: B. Carbon Monoxide pollution occurs primarily from emissions produced by fossil fuel powered engines. The incomplete reaction of air with fuel produces the colourless, odourless and highly toxic gas. The main issue with Carbon Monoxide is its health effects. It is capable of binding to the chemicals in our blood, called haemoglobin. It does so far more effectively than oxygen and also stays bound to the haemoglobin for far longer than oxygen does. The effect is that the blood is starved of oxygen, which then affects the rest of the body.

1. Smelting units
2. Pens and pencils
3. Paints
4. Hair oils and cosmetics

Codes:

Explanation: B. Smelting units and paints are the source of the lead poisoning.

1. In the production of plastic foams
2. In the production of tubeless tyres
3. In cleaning certain electronic components
4. As pressurizing agents in aerosol cans

Which of the statements given above is/are correct?

Explanation: C. Chlorofluorocarbons are used in the production of plastic foams, in cleaning electronic components and as pressurizing agents in aerosol cans.

1. It inactivates /kills the harmful microorganisms in water.
2. It removes all the undesirable odours from the water.
3. It quickens the sedimentation of solid particles, removes turbidity and improves the clarity of water.

Which of the statements given above is/are correct?

Explanation: A. Ultraviolet radiation inactivates / kills harmful micro organisms in water only.

1. Bagasse can be used as biomass fuel for the generation of energy.
2. Molasses can be used as one of the feedstocks for the production of synthetic chemical fertilizers.
3. Molasses can be used for the production of ethanol.

Select the correct answer using the codes given below.

Explanation: C. Bagasse is often used as a primary fuel source as it produces sufficient heat energy. Molasses can be used for the production of Ethanol. Ethanol is produced by the age old technique of fermentation of cereals, grams, molasses and other materials with high starch contents. Molasses is an inexpensive and readily available raw material. Molasses cannot be used as a synthetic fertilizer as molasses contain calcium, magnesium and Iron where as synthetic fertilizers are comprised of NPK i.e. Nitrogen, Phosphorous and Potassium.

Explanation: D. Acid rain is caused by a chemical reaction that begins when compounds of sulphur dioxide and nitrogen oxide react with molecules in the atmosphere to produce acids.

1. Crystallization of sodium chloride
2. Melting of ice
3. Souring of milk

Select the correct answer using the code given below.

Explanation: B. Chemical changes occur when a substance combines with another to form a new substance. Crystallization of sodium chloride is not a chemical as water of crystallization can be lost to get salt again. Similarly melting of ice is reversible .However souring of milk is a chemical change as it is not reversible and a new compound is formed.

1. Fly ash can be used in the production of bricks for building construction.
2. Fly ash can be used as a replacement for some of the Portland cement concrete.
3. Fly ash is made up of silicon dioxide and calcium oxide only, and does not contain any toxic elements.

Select the correct answer using the code given below.

Explanation: A. Fly ash brick (FAB) is a building material, specifically masonry units, containing class C fly ash and water. All fly ash includes substantial amounts of silicon dioxide (SiO2) aluminum oxide (Al2O3) and calcium oxide (CaO), the main mineral compounds in coal-bearing rock strata. Fly ash can be used as a replacement for some of the Portland cement contents of concrete.