Doubtly
@Doubtly · Joined Feb 2021
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- Explain the trend of the following in group 13 elements : A. atomic radii B. ionization enthalpy C. electron affinity A. Atomic radii: In group 13, on moving down the group, the atomic radii increases from B to Al. However, there is an anomaly observed in th... 1
- Give the formula of a compound in which carbon exhibit an oxidation state of A. +4 B. +2 C. -4 A. CCl₄ B. CO C. CH₄ 2
- PbCl4 is less stable than PbCl2 i. Pb has electronic configuration [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p². ii. Due to poor shielding of 6s² electrons by inner d and f electrons, it is diff... 1
- Ga3+ salts are better reducing agent while Tl3+ salts are better oxidising agent. i. Both gallium (Ga) and thallium (Tl) belong to group 13. ii. Ga is lighter element compared to thallium Tl. Therefore, its +3 oxidation st... 1
- Identify the group 14 element that best fits each of the following description. i. Carbon (C) ii. Carbon iii. Tin (Sn) and lead (Pb) iv. Carbon 2
- Which of the following shows most prominent inert pair effect ? a. C b. Si c. Ge d. Pb d. Pb shows most prominent inert pair effect 2
- Thallium shows different oxidation state because …………… a. of inert pair effect b. it is inner transition element a. of inert pair effect Thallium shows different oxidation state because of inert pair effect 1
- Haber’s process is used for preparation of …………. a. HNO3 b. NH3 c. NH2CONH2 d. NH4OH b. NH3 Haber’s process is used for preparation of b. NH3 2
- ………… is inorganic graphite. a. borax b. diborane c. boron nitride d. colemanite c. boron nitride is inorganic graphite. 2
- Which of the following is not an allotrope of carbon ? a. buckyball b. diamond c. graphite d. emerald d. emerald is not an allotrope of carbon 2
- If 0.2 mol of the following substances are required how many grams of those substances should be taken? (i) We know that, Molar mass= sum of constituent atomic masses Molar mass of NaCl= 23 + 35.5 = 58.5 g/mol Number of moles of a substance= Mo... 1
- Deduce the number of molecules of the following compounds in the given quantities. (i) 32g oxygen, (ii) 90g water (i) 32 g of oxygen : Molecular mass of O_(2 )= 2x16=32 Number of moles of O_(2 )= Mass of O₂ in grams/Molecular mass of O_(2 )= 32/32 = 1mol... 1
- Two samples ‘m’ and ‘n’ of slaked lime were obtained from two different reactions. The details about their composition Slaked lime have two samples ‘m’ and ‘n’ Sample m Mass :7g Mass of constituent oxygen :2g Mass of constituent calcium :5g In sample m, the r... 1
- Write the names of the following compounds and deduce their molecular masses. (i) Na₂SO_(4 )- Sodium sulphate. Molecular mass= sum of masses of individual components Atomic mass of, Na = 23u, S=32u, O=16u ∴ Molecular m... 1
- Explain with examples what is meant by a 'mole' of a substance. A mole is that quantity of a substance whose mass in grams is equal in magnitude to the molecular mass of that substance in daltons. The SI... 1
- What is meant by Unified Atomic Mass Instead of relative atomic mass, it is now possible to determine atomic masses in kg. The Unified Atomic Mass Unit or Dalton is a standard u... 2
- Explain the need for a reference atom for atomic mass. Give some information about two reference atoms. Since the atom is very very small it is very difficult to determine its mass very accurately, Hence the concept of the relative mass was As... 1
- M is a bivalent metal. Write down the steps to find the chemical formulae of its compounds formed with the radicals, M is a bivalent metal that is : M²⁺ Step 1 : Write the symbols and valencies of of M and sulphate. Symbols M SO₄ Valency 2 2 Step 2 : Cross-... 1