Chapter 1: Previous Year Paper – 2021 (Term- I)
Time allowed: 2 hours MaximumMarks: 40
General Instructions:
Read the following instructions very carefully and strictly follow them:
1. This question paper comprises 15 questions. All questions are compulsory. (ii) (iii) (iv) (v) (vi) 1. 2. 3. 4.
2. This question paper is divided into three sections Section A, B and C.
3. SECTION A: Questions No. 1 to 7 are short answer type questions. Each question carries 2 marks.
4. Section B: Questions No. 8 to 13 are also short answer type questions. Each question carries 3 marks.
5. Section C: Questions No. 14 and 15 are case-based questions. Each question carries 4 marks.
6. Internal choices have been provided in some questions. Only one of the alternatives has to be attempted.
SECTION A
1. a.) Write the molecular formula of the following carbon compounds:
(i) Methane
Answer. The molecular formula of methane isCH₄.
(ii) Propane
Answer: The molecular formula of propane isC₃H₈.
b.) Carbon compounds have low melting and boiling points. Why?
Answer: Carbon compounds, particularly hydrocarbons, tend to have low melting and boiling points because:
i. They generally consist of molecules held together by weak intermolecular forces like van der Waals forces (dispersion forces).
ii. These forces are much weaker compared to covalent or ionic bonds, meaning less energy is required to break these forces and change the state of the compound (solid to liquid or liquid to gas).
2. The electrons in the atoms of two elements X and Y are distributed in three shells having 1 and 7 electrons respectively in their outermost shells.
(a) Write the group numbers of these elements in the Modern Periodic Table.
Answer:X: Since element X has 1 electron in its outermost shell, it belongs toGroup 1 (alkali metals) of the Modern Periodic Table.
Y: Since element Y has 7 electrons in its outermost shell, it belongs toGroup 17 (halogens) of the Modern Periodic Table.
(b) Write the molecular formula of the compound formed when X and Y combine with each other.
Answer: Element X (Group 1) will lose 1 electron to become positively charged (cation), and element Y (Group 17) will gain 1 electron to become negatively charged (anion).
Therefore, they will combine in a 1:1 ratio to form a neutral compound. The molecular formula of the compound formed isXY.
(c) Which of the two is electropositive?
Answer: ElementX is electropositive. Electropositive elements tend to lose electrons easily. Since X has 1 electron in its outermost shell, it will likely lose that electron and form a cation, making it electropositive.
ElementY, on the other hand, is electronegative, as it tends to gain electrons to complete its outer shell.
3. a) Which of the following flowers will have higher possibility of self-pollination?
Mustard, Papaya, Watermelon, Hibiscus
Answer: Mustard flowers have a higher possibility of self-pollination due to their structure, while papaya, watermelon, and hibiscus mainly rely on cross-pollination.
b) List the two reproductive parts of a bisexual flower.
Answer:Stamens (Male reproductive part) andPistil (Female reproductive part)
4. Which one of the two multicellular organisms - Spirogyra and Planaria reproduces by regeneration and why? Give an example of any other organism which can also reproduce by the same process.
Answer:Planaria reproduces by regeneration. This means that if a p
