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Correct option is (a) Atoms & MOLECULES

Easy explanation: Atoms & Molecules are the basic constituents because the matter is made up of molecules and a MOLECULE is made of atoms. Ions are either positively or negatively charged particles. Nuclei are the central PART of atoms. When seen in the microscopic level, atoms are the basic unit of matter.

Right CHOICE is (a) grants immortality

Explanation: “Elixir” is a magical or medical potion, that is USED to prolong life to an infinite extent. This is one of the main purposes of the study of chemistry in OLDEN days. It grants the PERSON who drinks it with eternal life or YOUTH. It’s sometimes equated with the philosopher’s stone.

Right option is (b) 6 CO2 + 6 H2O → C6H12O6 + 6 O2

Easy explanation: 6 CO2 + 6 H2O → C6H12O6 + 6 O2 is the balanced EQUATION because the number of atoms of different elements is the same on both SIDES. Rest of them do not have an equal number of atoms of different elements on both sides.

Correct answer is (b) False

For explanation I would say: There are limitations to Dalton’s atomic theory. Dalton’s atomic theory couldn’t explain the REASON for COMBINING atoms. He also couldn’t explain GASEOUS VOLUMES, because as per his view, different elements have different mass but this isn’t true. This is explained by GAY lussac’s law.

Right option is (C) Ammonia

To explain I would say: Ammonia is made up of nitrogen and HYDROGEN in a RATIO of 1:3 by atoms. The sugar solution is a homogeneous mixture. Hydrogen and SODIUM are elements.

Correct option is (d) y

The explanation: LET it be any COMPOUND, but one MOLE of a substance always contains Avogadro’s NUMBER of particles. In the above question, Avogadro’s number (6.022×10^23) is given by the letter “y”. so, in 1 mole of GLUCOSE, there is y number of particles.

Right option is (a) 342 amu

To explain I WOULD say: The individual MASS of carbon is 12 amu, the individual mass of hydrogen is 1 amu & the individual mass of oxygen is 16 amu. But sucrose has 12 carbons, 22 HYDROGENS and 11 oxygens, that is 12 x 12 + 22 x 1 + 11 x 16 = 342 amu.

Correct CHOICE is (c) Sugar solution

Explanation: Copper, GOLD, and water are PURE but sugar solution is a homogeneous MIXTURE. Copper, gold, and water are made of the same elements but sugar solution contains sugar as solute and water as a solvent.

The correct choice is (B) Precision

For explanation: Precision is referred to as the closeness of different measurements for the same QUANTITY. ACCURACY is the degree to which it’s taken as STANDARD or almost EQUIVALENT to it.

Correct answer is (c) ALCHEMY

The explanation is: Alchemy is the STUDY of how a substance changes to other SUBSTANCES. It’s a very old study. In olden days, it used to be done in secrecy and was a mystery. It’s related to magic and ASTROLOGY. The MAIN thing practitioners concentrated in alchemy was turning lead into gold.

Correct option is (a) 342g

Easy explanation: One mole of SUCROSE is C12H22O11 The INDIVIDUAL mass of CARBON is 12 amu, the individual mass of hydrogen is 1 amu & the individual mass of OXYGEN is 16 amu. But sucrose has 12 CARBONS, 22 hydrogens and 11 oxygens, that is 12 x 12 + 22 x 1 + 11 x 16 = 342g.

Right answer is (a) Compound

The best I can EXPLAIN: Compound is a combination of two or more elements in a FIXED ratio. ELEMENT is made up of the same atoms. ATOM is the basic unit of life. Ion is either POSITIVELY or negatively charged.

The CORRECT answer is (a) 15.001 amu

To ELABORATE: The formula for finding the average atomic mass of an element is given by Avg. Atomic Mass = ∑Abundance of ISOTOPE x Mass of isotope. So for NITROGEN, avg atomic mass = 99.69 x 14.0031 + 0.39% x 15.0001 = 14.007.

Right option is (b) 43,200 seconds

Best explanation: Half day means 12 hours. ONE hour means 60 seconds. And each MINUTE is of 60 seconds. In the above QUESTION, we need the TOTAL number of seconds so 12 X 60 x 60 seconds = 43,200 seconds.

Correct option is (C) One mole is the AMOUNT of a substance that contains as many particles as there are atoms in exactly 12 g of the carbon atom

The explanation is: The corrected statements are as follows: the value of Avogadro’s NUMBER is 6.022×10^23 atoms, one molecule of any substance contains Avogadro’s number of particles & 1 u = Ma/NA. The correct option is that one mole is the amount of a substance that contains as many particles as there are atoms in exactly 12 g of the carbon atom.

Correct option is (c) 6.022 x 10^23 particles

The best I can explain: The answer is Avogadro’s NUMBER. One mole of any substance CONTAINS Avogadro’s number of particles. Avogadro number DENOTED by NA. Its value is 602213670000000000000000, also written as 6.022×10^23.

Right answer is (a) Law of Multiple Proportions

The BEST I can explain: Two or more elements those are given, may combine to FORM more than one COMPOUND, the masses of one ELEMENT that will combine with the given mass of the other elements, would be in the ratio of whole NUMBERS is the law of Multiple Proportions.

Right choice is (a) Chemical

Explanation: Chemical properties are combustibility, COMPOSITION, REACTIVITY with acids & BASES, etc. So to observe them chemical change has to occur. Combustibility can be known only when extinguished with fire. Composition is a chemical property because we can’t find a COMPOUND’s composition just by LOOKING at it. We need to run some chemical tests to find out etc

Right answer is (a) Limiting reagent

Explanation: THOUGH the other substances are excess in AMOUNT than the required, each and every reactant needs to be in a fixed ratio to ATTAIN the desired product. So, thereby, the reactant that limits the QUANTITY of the product formed is called limiting reagent and this reactant GETS consumed first completely.

Correct CHOICE is (d) 0.6

The best EXPLANATION: The chemical equation of formation of magnesium oxide is 2 MG(s) + O2(g) ® 2MgO(s). The formula for calculation of mass PERCENT is (mass of solute/mass of solution) X 100. Therefore 2(24)/2(24+16) = 0.6.

The correct ANSWER is (b) 2 moles of OXYGEN

The explanation is: One mole of any substance contains Avogadro’s number of particles. Its VALUE is 6.022×10^23 atoms. But here it’s given 12.044 x 10^23 atoms, thereby dividing it by Avogadro’s number; 12.044 x 10^23 atoms/6.022×10^23 atoms = 2 moles. Hence it contains 2 moles of oxygen.

Correct choice is (d) LAW of Conservation of volume

To EXPLAIN: FIVE basic laws are required to govern the combination of elements to FORM COMPOUNDS. They are Law of Conservation of Mass, Law of Definite Proportions, Law of Multiple Proportions, Gay Lussac’s Law of Gaseous Volumes, and Avogadro’s Law.

Right option is (a) 10^-24, 10^-18

To EXPLAIN: Yocto is 10 power (-24) and atto is 10 power (-18). These are the standard PREFIXES USED in S.I. SYSTEM.

Correct choice is (B) False

For explanation: One must know the mass percent of each and every element of a compound to CALCULATE an empirical formula. As an empirical formula is the simplest whole number RATIO of VARIOUS atoms present in a compound.

Right choice is (d) COMPOSITION

To explain I would say: Composition is a chemical property because we can’t find a COMPOUND’s composition just by looking at it. We need to run some chemical TESTS to find out. Odor, color, and DENSITY are physical PROPERTIES, as we can find them just by looking at them.

Correct option is (a) VARAHMIHIR’s Brihat Samhitha

Explanation: Varahmihir’s Brihat Samhitha is about how glutinous material is prepared and applications of it on roofs and walls of houses and temples. Ajanta and Ellora’s walls look bright for ages only because the SCIENCE mentioned in this book. It contains the science of USING fruits, plants, ETC to paint.

Correct choice is (a) mole

The best I can explain: One mole is the amount of a substance that contains as many particles as there are atoms in EXACTLY 12 g of the carbon ATOM. So S.I. the system took mole as the seventh base fundamental quantity (SYMBOL = mol).

The correct ANSWER is (d) GAY Lussac’s Law of Gaseous Volumes

Easy explanation: When gases combine or as written in a chemical reaction they combine in a simple RATIO by VOLUME, PROVIDED that all gases are at the same temperature and given pressure, this is called Gay Lussac’s Law of Gaseous Volumes and is proposed by Joseph Louis.

Correct answer is (a) precise

Easiest explanation: These VALUES are precise as they are close to each other but are not ACCURATE. Precision is referred to as the closeness of DIFFERENT MEASUREMENTS for the same QUANTITY. Accuracy is the degree to which it’s taken as standard or almost equivalent to it.

Right answer is (B) 4

To elaborate: The non-zero digits and any zeros between them are all significant. Since there is no DECIMAL, zeros are not significant. THEREFORE it’s 4.

The correct choice is (c) 66g

The explanation is: The CHEMICAL balanced equation for combustion of methane is CH4(g) + 2O2(g)→CO2(g) + 2H2O(g). From the above equation, 1 mole of methane GIVES 1 mole of carbon dioxide. But 20G of methane = 1.25 moles, therefore it gives 1.25 moles of carbon dioxide = 44(1.5) = 66g.

Correct ANSWER is (c) An equal number of molecules on both the side

For explanation: A balanced reaction may not have an equal number of molecules on both the sides, because molecules may COMBINE into one or a single molecule may breakdown into TWO or more. IT can disassociate or UNDERGO double decomposition.

Correct choice is (a) actual whole NUMBERED ratio

Easy explanation: Actual whole numbered ratio is correct because the molecular formula is the exact number of different TYPES of atoms present in the molecule of a compound. RATIONAL may be fractional or DECIMAL, simplest possible whole numbered is empirical.

Correct OPTION is (b) Empirical

Best explanation: An empirical FORMULA is the simplest whole number RATIO of various atoms PRESENT in a compound. The molecular formula is the exact number of different types of atoms present in the MOLECULE of a compound.

Right option is (a) True

Explanation: 1 amu is defined as a mass that is almost equal to ONE-twelfth of the mass of one carbon – 12 atom. It is a unit to MEASURE atomic and MOLECULAR mass. The carbon atom is taken relatively here. And also 1 amu = 1.66056×10^-24 g.

The CORRECT choice is (a) True

Explanation: Each and every element has a different mass. For example, CARBON’s molecular weight is 12.0107 u, OXYGEN’s molecular weight is 15.999 u and nitrogen’s molecular weight is 14.0067 u. Hence it’s different for different ELEMENTS.

Right choice is (a) JOSEPH PROUST

The best explanation: Joseph Proust WORKED about the composition of ELEMENTS present in a compound experimentally, he concluded that from any source, a PARTICULAR compound always contains the same elements in the same proportion by mass/weight.

Correct answer is (b) 5

Explanation: Five basic laws are REQUIRED to GOVERN the combination of ELEMENTS to form COMPOUNDS. They are LAW of Conservation of Mass, Law of Definite Proportions, Law of Multiple Proportions, Gay Lussac’s Law of Gaseous Volumes, and Avogadro’s Law.

The correct ANSWER is (a) True

Explanation: On a BULK level, the matter is divided as a MIXTURE and pure SUBSTANCES.

Right CHOICE is (c) Elements and Compounds

Easiest EXPLANATION: Elements and Compounds together make pure SUBSTANCES, as they have fixed COMPOSITIONS.

Right answer is (b) False

The best I can explain: The preparation of gun powder is EXPLAINED in Rasopanishada. It’s an ANCIENT ALCHEMY book that DESCRIBES gun powder. It also describes the making of fireworks with sulfur, saltpeter, charcoal, arsenic, camphor, mercury, etc.

The CORRECT choice is (a) Mixture

The best explanation: Mixture is a COMBINATION of pure substances in a ratio. Pure substances which are in its COMPOSITION are called its COMPONENTS. Atom is the BASIC unit of life.

The correct choice is (b) Rusting of IRON

Explanation: In rusting of iron, the oxidation state of iron changes, but in the conversion of water to ice, crumpling a sheet of aluminum FOIL and casting silver the chemical state remains same whereas the PHYSICAL state changes. When iron is exposed to oxygen, iron oxide formation takes place.