In Class 11 Final Exams there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Downloads of CBSE Class 11 Chemistry Chapter 1 Case Study and Passage-Based Questions with Answers were Prepared Based on the Latest Exam Pattern. Students can solve Class 11 Chemistry Case Study Questions Some Basic Concepts of Chemistry to know their preparation level.
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In CBSE Class 11 Chemistry Paper, There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.
Some Basic Concepts of Chemistry Case Study Questions With Answers
Here, we have provided case-based/passage-based questions for Class 11 Chemistry Chapter 1 Some Basic Concepts of Chemistry
Case Study/Passage-Based Questions
Case Study 1: The uncertainty in the experimental or the calculated values is indicated by mentioning the number of significant figures. Significant figures are meaningful digits that are known with certainty plus one which is estimated or uncertain. The uncertainty is indicated by writing the certain digits and the last uncertain digit. there are certain rules for determining the number of significant figures. These are stated below:
- All non-zero digits are significant. For Example in 285 cm, there are three Significant figures and in 0.25 mL, there are two significant figures.
- Zeros preceding to first non-zero digit are not significant. such zero indicates the position of the decimal point. thus, 0.03 has one significant figure and 0.0052 has two significant figures.
- Zeros between two non-zero digits are significant. thus, 2.005 has four Significant figures.
- Zeros at the end or right of a number are significant, provided they are on the right side of the decimal point. For example, 0.200 g has three significant figures. But, if otherwise, the terminal zeros are not significant if there is no decimal point.
Precision refers to the closeness of various measurements for the same quantity. However, accuracy is the agreement of a particular value to the true value of the result.
LAWS OF CHEMICALCOMBINATIONS- The combination of elements to form compounds is governed by the following five basic laws.
1) Law of Conservation of Mass-This law was put forth by Antoine Lavoisier in 1789. He performed careful experimental studies for combustion reactions and reached the conclusion that in all physical and chemical changes, there is no net change in mass during the process. Hence, he reached the conclusion that matter can neither be created nor destroyed. This is called the ‘Law of Conservation of Mass’.
2) Law of Definite Proportions-This law was given by, a French chemist, Joseph Proust. He stated that a given compound always contains exactly the same proportion of elements by weight.
3) Law of Multiple Proportions-This law was proposed by John Dalton. According to this law, if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in the ratio of small whole numbers. For example, hydrogen combines with oxygen to form two compounds, namely, water and hydrogen peroxide.
Hydrogen + Oxygen→ Water
2g 16g 18g
Hydrogen + Oxygen → Hydrogen Peroxide
2g 32g 34g
Here, the masses of oxygen (i.e., 16 g and 32 g), which combine with a fixed mass of hydrogen (2g) bear a simple ratio, i.e., 16:32 or 1:2.
4) Gay Lussac’s Law of Gaseous Volumes-This law was given by Gay Lussac in 1808. He observed that when gases combine or are produced in a chemical reaction they do so in a simple ratio by volume, provided all gases are at the same temperature and pressure.
5) Avogadro’s Law – In 1811, Avogadro proposed that equal volumes of all gases at the same temperature and pressure should contain an equal number of molecules.
In 1808, Dalton published ‘A New System of Chemical Philosophy, in which he proposed the following :
1.) Matter consists of indivisible atoms.
2.) All atoms of a given element have identical properties, including identical mass. Atoms of different elements differ in mass.
3.) Compounds are formed when atoms of different elements combine in a fixed ratio.
4.) Chemical reactions involve the reorganization of atoms. These are neither created nor destroyed in a chemical reaction.
[A[ Multiple Choice Question
1) … refers to the closeness of various measurements for the same quantity.
- a) Accuracy
- b) Reliability
- c) Precision
- d) Uncertainty
Ans – c) Precision
2) Law of Conservation of mass was put forth by ….in 1789.
- a) Joseph Proust
- b) Antoine Lavoisier
- c) Joseph Louis
- d) Gay Lussac
Ans – b) Antoine Lavoisier
3) Which of the following number has two significant figures.
- a) 00052
- b) 052
- c) 52
- d) 0052
Ans – d) 0.0052
4) … is the agreement of a particular value to the true value of the result.
- a) Accuracy
- b) Reliability
- c) Precision
- d) Uncertainty
Ans – a) Accuracy
5) Law of Multiple Proportions proposed by.
- a) Joseph Proust
- b) Antoine Lavoisier
- c) Joseph Louis
- d) John Dalton
Ans – d) John Dalton
Case Study 2: The identity of a substance is defined not only by the types of atoms or ions it contains but by the quantity of each type of atom or ion. The experimental approach required the introduction of a new unit for the number of substances, the mole, which remains indispensable in modern chemical science. A mole is an amount unit similar to familiar units like pair, dozen, gross, etc. It provides a specific measure of the number of atoms or molecules in a bulk sample of matter. A mole is defined as the amount of substance containing the same number of discrete entities (atoms, molecules, ions, etc.) as the number of atoms in a sample of pure 12C weighing exactly 12g. One Latin connotation for the word “mole” is “large mass” or “bulk,” which is consistent with its use as the name for this unit. The mole provides a link between an easily measured macroscopic property, bulk mass, and an extremely important fundamental property, the number of atoms, molecules, and so forth. The number of entities composing a mole has been experimentally determined to be 6.02214179 × 1023.
6.02214179 × 1023, a fundamental constant named Avogadro’s number (NA ) or the Avogadro constant in honor of Italian scientist Amedeo Avogadro. This constant is properly reported with an explicit unit of “per mole,” a conveniently rounded version being 6.022×1023/mol. Consistent with its definition as an amount unit, 1 mole of any element contains the same number of atoms as 1 mole of any other element. The masses of 1 mole of different elements, however, are different, since the masses of the individual atoms are drastically different. The molar mass of an element (or compound) is the mass in grams of 1 mole of that substance, a property expressed in units of grams per mole (g/mol).
(i) A sample of copper sulfate pentahydrate contains 8.64 g of oxygen. How many grams of Cu is present in the sample?
(a) 0.952g
(b) 3.816g
(c) 3.782g
(d) 8.64g
Answer: (b) 3.816g
(ii) A gas mixture contains 50% helium and 50% methane by volume. What is the percent by \ weight of methane in the mixture?
(a) 19.97%
(b) 20.05%
(c) 50%
(d) 80.03%
Answer: (d) 80.03%
(iii) The mass of oxygen gas which occupies 5.6 liters at STP could be
(a) gram atomic mass of oxygen
(b) one-fourth of the gram atomic mass of oxygen
(c) double the gram atomic mass of oxygen
(d) half of the gram atomic mass of oxygen
Answer: (b) one fourth of the gram atomic mass of oxygen
(iv) What is the mass of one molecule of yellow phosphorus? (Atomic mass of phosphorus = 30)
(a)1.993 x 10-22 mg
(b)1.993 x 10-19 mg
(c) 4.983 x 10-20 mg
(d) 4.983 x 10-23 mg
Answer: (d) 4.983 x 10-23 mg
(v) The number of moles of oxygen in 1L of air containing 21% oxygen by volume, in standard conditions is
(a) 0.186 mol
(b) 0.21 mol
(c) 2.10 mol
(d) 0.0093 mol
Answer: (d) 0.0093 mol
Case Study 3: Chemistry plays an important role in human needs for food, health care products, and improving life. Cis platin and taxol are used in chemotherapy, and AZT (Azidothymidine) is used for AIDS. SI units are international units of measurement. The matter is classified into elements, compounds, and mixtures, which can be homogeneous as well as heterogeneous. A mixture can be separated by physical methods, compounds can be separated by chemical methods only. Atomic mass is the average of masses of isotopes depending upon their natural abundance. The empirical formula is calculated with the help of the percentage composition of elements in a compound and molecular mass helps to calculate the molecular formula. A chemical equation must be balanced so as to follow the laws of chemical combination.
Which of the following are used in chemotherapy?
A) Taxol
B) AZT
C) Cis platin
D) A and C
E) A, B, and C
Answer: D
What are SI units?
A) Chemical formulas
B) Units of time
C) International units of measurement
D) Isotopes
Answer: C
How can a compound be separated?
A) Physical methods
B) Chemical methods
C) Both physical and chemical methods
D) None of the above
Answer: B
What does the atomic mass of an element represent?
A) Mass of a single atom
B) Mass of all isotopes combined
C) Average mass of isotopes based on natural abundance
D) Mass of the most common isotope
Answer: C
Which of the following statements is true regarding a chemical equation?
A) It does not need to be balanced
B) It must be balanced according to the laws of chemical combination
C) It represents only the physical states of the reactants
D) It includes only empirical formulas
Answer: B
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