11th
In this category students supposed to ask questions which belong to std 11th maharashtra board Science
- At Andaman, authorities do not allow tourists to collect shells from beaches. Why it must be so? Seashells are an important part of the coastal ecosystem and are crucial for the survival of various marine creatures. They provide material... 1
- Riya found peculiar plant on her visit to Himachal Pradesh. What are the ways she can show it to her biology teacher and get information about it? Riya can press and mount the plant specimen on a herbarium sheet and preserve the dried plant material, until she returns back from her visi... 1
- Jijamata Udyan, the famous zoo in Mumbai has acclimatised humbolt penguins. Zoological park (zoo) is a type of ex-situ conservation in which wild animals are kept in captivity. Humboldt penguins are native to South A... 1
- Distinguish between botanical gardens, zoological park and biodiversity park with reference to characteristics Botanical Gardens Zoological Parks Biodiversity Parks Plants of different varieties collected from different parts of the world are grown in... 1
- A group of students found two cockroaches in the classroom. They had a debate whether they are alive or dead. (c) Irritability 2
- A particular plant is strictly seasonal plant. Which one of the following is best suited if it is to be studied in the laboratory (a) Herbarium 2
- Which is not a property of living being? a. Metabolism b. Decay c. Growth d. Reproduction correct option is b. Decay 2
- How the atomic size vary in a group and across a period? Explain with suitable example. Answer: Atomic size increases down a group and decreases from left to right across a period. Down a group: each new element has one more she... 1
- Define ionization enthalpy. Name the factors on which ionisation enthalpy depends? How does it vary down the group and across a period? Variation of ionization energy down the group: On moving down the group, the ionization enthalpy decreases. This is because the electron is... 2
- What are the valence electrons ? For s-block and p-block elements show that number of valence electrons is equal to its group number. Electrons present in the outermost shell of the atom of an element are called valence electrons. 3Li is an s-block element and its electroni... 1
- Compare chemical properties of metals and non metals. The difference in chemical properties between metals and nonmetals. Nonmetals Metals 1. Nonmetals form acidic or neutral oxides when they re... 1
- Explain : electronegativity and electron gain enthalpy. Which of the two can be measured experimentally? The ability of a covalently bonded atom to attract the shared electrons toward itself is called electronegativity (EN). Electronegativity ca... 1
- Why the elements belonging to the same group do have similar chemical properties ? Chemical properties of elements depend upon their valency.Elements belonging to the same group have the same valency. Hence, the elements be... 1
- Why the second ionization enthalpy is greater than the first ionization enthalpy ? The second ionization enthalpy (Δ_iH₂) is greater than the first ionization enthalpy (Δ_iH₁) as it involves removal of electron from the pos... 1
- Explain the screening effect with a suitable example. In a multi-electron atom, the electrons in the inner shells tend to prevent the attractive influence of the nucleus from reaching the outerm... 1
- Ionization enthalpy of Li is 520 kJ mol-1 while that of F is 1681 kJ mol-1. Explain. Both Li and F belong to period 2. Across a period, the screening effect is the same while the effective nuclear charge increases. As a resul... 1
- La belongs to group 3 while Hg belongs to group 12 and both belong to period 6 of the periodic table. La and Hg both belong to period 6. Therefore, n = 6. Elements of group 3 to group 12 belong to the d-block of the modern periodic table. The... 1
- Complete the following table : Assign oxidation number to the underlined species and write Stock notation of compound Compound Oxidation number Stock notation Compound Oxidation number Stock notation AuCl₃ +3 Au(III)Cl₃ SnCl₂ +2 Sn(II)Cl₂ ceunderlineV₂O⁴⁻₇ +5 ceV2(V)O⁴-₇ ceunderlinePtCl²-₆ +4 cePt(... 1
- In which reaction does nitrogen exhibit variation of oxidation state from -3 to +5 ? In the following series of reactions, the oxidation number of nitrogen changes from –3 in NH3 to +5 in HNO3. −3 +2 ceundersetAmmonia4NH3_((g... 1
- In which chemical reaction does carbon exibit variation of oxidation state from -4 to +4 ? Write balanced chemical reaction. In combustion of methane, carbon exhibits variation from -4 to +4. The reaction is as follows: CH₄ + 2O₂ → CO₂ + 2H₂O In CH₄, the oxidation... 1
- Write the formula for the following compounds : A. Mercury(II) chloride B. Thallium(I) sulphate C. Tin(IV) oxide D. Chromium(III) oxide A. HgCl₂ B. Tl₂SO₄ C. SnO₂ D. Cr₂O₃ 2
- Predict the shape and bond angles in the following molecules: a. CF4 b. NF3 c. HCN d. H2 S CF₄: tetrahedral, 109°28′; NF₃: trigonal pyramidal, about 102°; HCN: linear, 180°; H₂S: bent (angular), about 92°. a. CF₄ : C has 4 bond pai... 1
- Define : a. Bond Enthalpy b. Bond Length a. Bond enthalpy is the amount of energy required to break one mole of bonds of a particular type between two atoms in the gaseous state. It... 1
- In case of bond formation in Acetylene molecule : a. How many covalend bonds are formed ? Acetylene ( mathrmH-CequivC-H ): a. 5 covalent bonds; b. 3 σ bonds and 2 π bonds; c. sp hybridisation. a. There are two C–H single bonds and... 1