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CBSE Class 1. 1th Chemistry Chapter 1. The p- Block Elements.

AskIITians offers tutorials on all significant topics of Chemistry including Physical Chemistry, Inorganic Chemistry & Organic Chemistry. Refer the revision notes to. These pages provide a brief review of a number of general chemistry topics. Choose one of the categories below or scroll down to see a complete list of all the pages. Air France announced this week it is launching Joon, a new airline “especially aimed at a young working clientele, the millennials,” and more specifically the. KVS Notes Chemical Bonding and Molecular Structure CBSE class 11 Chemistry Key notes and summary of the chapter with examples. These notes are prepared by ZIET. Physical Setting/ Physical Setting/ Chemistry Chemistry Core Curriculum THE UNIVERSITY OF THE STATE OF NEW YORK THE STATE EDUCATION DEPARTMENT. The World of Chemistry The relationships of chemistry to the other sciences and to everyday life are presented. Color The search for new colors in the mid 1800s.

NCERT Solutions Class 1. Chemistry. Chemistry Lab Manual. Chemistry Sample Papers. NCERT TEXTBOOK QUESTIONS SOLVEDQuestion 1. Discuss the pattern of variation in the oxidation states of (i) B to Tl (ii) C to Pb. Answer:  (i) B to Tl. Best Rc Lap Counter Software Programs on this page. Common oxidation states are +1 and +3.

The stability of +3 oxidation state decreases from B to Tl. Stability of +4 oxidation state decreases from C to Pb. Details can be seen from the text part. Question 2. How can you explain higher stability of BCl. Tl. Cl. 3? Answer: BCl. Because there is absence of d- and f- electrons in boron three valence electrons (2s.

In Tl the valence s- electron (6s. Thus, only 6p. 1 electron is available for bonding. Therefore, BCl. 3 is stable but Tl.

Cl. 3 is comparatively unstable. Question 3. Why does borontrifluori. Lewis acid? Answer: In BF3, central atom has only six electrons after sharing with the electrons of the Fatoms. It is an electron deficient compound and thus behaves as a Lewis acid.

Question 4. Consider the compounds, BCl. CCl. 4. How will they’behave with water justify? Answer: In BCl. 3, there is only six electrons in the valence shell of B atom. Thus, the octet is incomplete and it can accept a pair of electrons from water and hence BCl. Whereas, in CCl. 4, C atom has 8 electrons and its octet is complete.

That’s why it has no tendency to react with water. CCl. 4 + H2. 0 —————> No reaction. Question 5. Is boric acid a protonic acid?

Explain. Answer: Boric acid is a Lewis acid, it is not a protonic acid. Boric acid accepts electrons from hydroxyl ion of H2. B (OH)3 + 2. HOH ————> . Explain what happens when boric acid is heated.

Answer: On heating boric acid above 3. K, it forms metaboric acid, HB0. B2. O3. Question 7. Describe the shapes of BF3 and BH4–. Assign the hybridisation of boron in these species. Answer: In BF3, boron is SP2 hybridized.

Write reactions to justify amphoteric nature of aluminium. Answer: Aluminium reacts with acid as well as base.

This shows amphoteric nature of aluminium. Al(s) + 6. HCl(dil.) ——> 2. Al. Cl. 3(aq) + 3. H2(g)2. Al(s) + 2. Na. OH(aq) + 6. H2. O(l) ———- > 2.

Na+ . What are electron deficient compounds? Are BCl. 3 and Si. Cl. 4 electron deficient species? Explain. Answer: Electron deficient species are those in which the central atom in their molecule has the tendency to accept one or more electron pairs. They are also known as Lewis acid. BCl. 3 and  Si. Cl. Since, in BCl. 3, B atom has only six electrons.

Therefore, it is an electron deficient compound. In Si. Cl. 4 the central atom has 8 electrons but it can expand its covalency beyond 4 due to the presence of d- orbitals. Thus, Si. Cl. 4 should also be considered as electron deficient species. Question 1. 0. Write the resonance structure of CO3. HCO3– . Answer: Question 1. What is the state of hybridisation of carbon in (a) CO3.

Answer: (a) CO3. 2- (sp. Diamond (sp. 3) (c) Graphite (sp. Question 1. 2. Explain the difference in properties of diamond and graphite on the basis of their structures. Answer: Since diamond exists as a three dimensional network solid, it is the hardest substance known with high density and high melting point.

Whereas in graphite, any two successive layers are held together by weak forces of attraction. This makes graphite soft. In graphite, carbon atom is sp. Unlike diamond, graphite is good conductor of heat and electricity. Question 1. 3. Rationalise the given statements and give chemical reactions: Lead (II) chloride reacts with Cl. Pb. Cl. 4 . Lead (IV) chloride is highly unstable towards heat. Lead is known not to form an iodide Pbl.

Answer: Pb. Cl. 2  + Cl. Crack Shack Or Mansion Ipad Cases. Pb. Cl. 4. This is because Pb can show +2 oxidation state more easily than +4 due to inert pair effect. Pb. Cl. 4 ———> Pb. Cl. 2 + Cl. 2Because Pb. Pb. 4+ due to inert pair effect.

Pbl. 4 does not exist because I- ion being a powerful reducing agent reduces Pb. Pb. 2+ ion in solution. Pb. 4+ + 2. I– ——- > Pb.

Pb(IV)                       Pb(II)Question 1. Suggest reason why the B- F bond lengths in BF3 (1. BF– (1. 43 pm) differ. Answer: In BF3 . Thus, the difference in bond length is due to the state of hybridisation. Question 1. 5. If B- Cl bond has a dipole moment, explain why BCl. Answer: B- Cl bond has dipole moment because of polarity. In BCl. 3 since the molecule is symmetrical (planar).

Thus the polarities cancel out. Question 1. 6. Aluminium trifluoride is insoluble in anhydrous HF but dissolves on addition of Na. F. Aluminium trifluoride precipitates out of the resulting solution when gaseous BF3 is bubbled through. Give reason. Answer: Since, anhydrous HF is covalent compound and weak acid due to high bond dissociation energy.

Al. F3 does not dissolve in HF. Whereas Na. F is ionic compound. Na. F + Al. F3 ———> Na. Suggest a reason as to why CO is poisonous. Answer: CO reacts with haemoglobin to form carboxyhaemoglobin which can destroy the oxygen carrying capacity of haemoglobin and the man dies of suffocation. Question 1. 8. How is excessive content of C0.

Answer: Excess of C0. Some of it is dissipated into the atmosphere while the remaining part is radiated back to the earth. As a result, temperature of the earth increases. This is the cause of global warming. Question 1. 9. Explain structures ofdiborane and boric acid. Answer: Boric acid contains planar BO3.

Question 2. 0. What happens when (a) Borax is heated strongly (b) Boric acid is added to water (c) Aluminium is treated with dilute Na. OH (d) BF3 is reacted with ammonia? Answer: Question 2.

Explain the following reactions. Give reasons: (i) Cone. HNO3 can be transported in aluminium container.

HNO3 to form a very thin film of aluminium oxide on its surface which protects it from further reaction. Al(s) + 6. HNO3(conc.)———> Al. O3(s) + 6. NO2(g) + 3. H2. O(l)(ii) Na. OH reacts with Al to evolve H2 gas. Thus the pressure of the gas produced can be used for clogged drains. Al(s) + 2. Na. OH(aq) + 2. H2. O(l) ——- > 2.

Na. Al. O2(aq) + 3. H2(g)(iii) Graphite has layered structure which are held by weak van der Waals forces. Thus, graphite cleaves easily between the layers, therefore it is very soft and slippery. That’s why it is used as lubricant.(iv) Diamond is used as an- abrasive because it is an extremely hard substance.(v) Alloys of aluminium, like duralumin, is used to make aircraft body due to some of its property like toughness, lightness and resistant to corrosion.(vi) Generally, aluminium metal does not react with water quickly but, when it is kept overnight, it reacts slowly with water in presence of air. Al(s) + O2(g) + H2.

O(l) ——–> Al. 2O3(S) + H2(g)a very small amount of (in ppm) Al. Aluminium is generally unaffected by air and moisture and it is also good conductor of electricity. That’s why it is used in transmission cables. Question 2. 3. Explain why is there a phenomenal decrease in ionization enthalpy from carbon to silicon. Answer: Because there is increase in atomic size on moving from carbon to silicon, the screening effect increases.

Thus the force of attraction of nucleus for the valence electron decreases as compared to carbon. Thus the ionization enthapy decreases from carbon to silicon. Question 2. 4. How would you explain the lower atomic radius of Ga as compared to Al? Answer: Due to poor shielding effect of d- electrons in Ga, the electrons in gallium experience great force of attraction by nucleus as compared to Al. Question 2. 5. What are allotropes? Sketch the structure of two allotropes of carbon namely diamond and graphite.

What is the impact of structure on physical properties of two allotropes? Answer:  Allotropes: Allotropes are the different forms of an element which are having same chemical properties but different physical properties due to their structures. In diamond, carbon is SP3 - hybridized. Since, diamond is three dimensional network solid, it is hardest substance with high density whereas graphite has a layered structure.