10th, Sci.I, Scientific reasons & Q 1 B

10th, Sci.I,  Scientific reasons 

 

विचारांचा प्रभाव मनावर पडतो, 

मनाचा प्रभाव शरीरावर पडतो,

 शरीर आणि मन या दोन्हींचाही प्रभाव जीवनावर पडत असतो

 म्हणून नेहमी चांगले विचार मनात आणावेत आणि 

समाधानी राहावे.🙏

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Today we will see the rest of class 10th scientific reasons.

1. Sodium is always kept in kerosene. (highly active, density, )
Ans:- 
•  At normal / room temperature sodium (Na) metal combines very strongly with oxygen O2. 
• Sodium metal reacts with Oxygen in the air, water vapor, and carbon dioxide. 
•  The density of Sodium is more than kerosene, so it sinks in it. Sodium does not react with kerosene. So sodium is always kept in kerosene.

꧁●○≛⃝ ≛⃝ 🌍○●꧂

2. Lemon or tamarind are used for cleaning copper vessels that turn greenish.
(Black copper oxide, green copper carbonate, acid)
Ans:-
•  Copper gets oxidized in the air to form black copper oxide. Copper oxide reacts slowly with carbon dioxide in the air and creates a green coating. This green substance is called copper carbonate.
•  Lemon contains citric acid and tamarind contains tartaric acid. This acid dissolves the green coating of basic copper carbonate and makes copper vessels shiny again.
• Therefore Lemon or tamarind are used for cleaning copper vessels that turn greenish.

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* Anodes need to be replaced from time to time during the electrolysis of alumina.
( Oxygen, erode carbon electrode)
• Ans:-1. In the process of electrolysis of alumina the Oxygen (O2) gas liberated at the carbon anode reacts with graphite (C) rods and forms carbon dioxide(CO2).
• 2. During electrolysis of alumina graphite rods continuously erode because they get oxidized.
• C +O2 ---> CO2
Hence Anodes need to be replaced from time to time during the electrolysis of alumina.

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* Calcium floats on water during the reaction with water.
( less vigorous reaction, insufficient heat, hydrogen gas sticks to calcium)
• Ans:- 1. Calcium metal reacts with water less vigorously therefore the heat evolved is not sufficient for hydrogen to catch fire.
• 2. The bubbles of hydrogen gas stick to the surface of sodium metal, so calcium floats on water.

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* Generally the ionic compounds have high melting points.
( strong electrostatic force, hard and solid )
Ans:- 
• 1. Ionic compounds are formed by a strong electrostatic force of attraction between oppositely charged ions. Therefore ionic compounds are hard and they exist in a solid state.
• 2. Large energy is required to overcome the intermolecular force of attraction of ionic compounds.
• Hence generally the ionic compounds have high melting points.

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* Carbon atoms are capable of forming an unlimited number of compounds.
( Tetravalent, Catenation, single, double or triple bond, Catenation)
Ans:- 
•  Tetravalent tendency:-
• Carbon atoms can bond with four other carbon atoms or atoms of other monovalent elements.
• Catenation:-
• Carbon atoms can share their valence electrons to form single, double, and triple bonds.
•  Multiple bonding:-
• Carbon atoms can form multiple bonds with themselves and other atoms, such as nitrogen, oxygen, or hydrogen.
•  Carbon atoms can also form straight chains, branched chains(isobutane), and rings [benzene (C6H6)].
• Hence Carbon atoms are capable of forming an unlimited number of compounds.

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* Geostationary satellites are not useful for the study of polar regions. Or
Why are geostationary satellites not useful for studies of polar regions.
( position, same speed, equator)
Ans:-
• Geostationary satellites orbit the Earth at the equator and rotate at the same speed as the Earth.
• Geostationary satellites remain fixed in the same position respective to the Earth's surface
• They do not fly about the polar regions.
Hence Geostationary satellites are not useful for the study of polar regions.

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* Ethylene is an unsaturated hydrocarbon.
(Definition, double bond.)
Ans:-
• 1. Definition:- Those hydrocarbons contain carbon carbon double or triple bonds they are called unsaturated hydrocarbons.
• 2. The ethylene molecule contains a carbon double bond.
• 3. This means the valencies of the two carbon atoms are not fully satisfied by a single covalent bond.
Hence ethylene is an unsaturated hydrocarbon.

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🎷 Today let's look at one more question type. In this question type, there is no need to write an explanation of the answer.
Q.1 B 

 
Q.1 B sets contents questions of the type "write the name/ molecular formula/ electronic configuration.

This question, Question No. 1(b), is carried for one mark.

• * Alkali metal from the second period            
Ans:- Lithium (Li)

• * Halogens in the 3rd period.      Ans:- Chlorine ( Cl )

• * Horizontal rows in the modern periodic table.            
Answer:- periods.

• * The element with electronic configuration 2,8,7            
Answer:- Chlorine (Cl)

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• * The elements with stable electronic configuration.
Answer:-  

1.  Helium (He),
2. Neon (Ne), 
3. Argon( Ar), 
4. Krypton (Kr), 
5. Xenon(Xe).

• Right two names of inert gas/ noble gas or 18 group elements.
Answer:- 1. Helium (He), Neon (Ne), Argon( Ar), krypton (Kr), xenon(Xe).


• * Three elements have 7 electrons in their outermost shell.
Right names of three elements belonging to the Halogen group.
Ans:- 1. Fluorine (F)
2. Chlorine (Cl)
3. Bromine(Br)
4. Iodine(I)

• * Two elements have a single electron in their outermost shell.
Or
• Write to names of alkali metals.
Ans:- 1. Lithium (Li)
2. sodium (Na)
3. potassium ( K)

• * An alkali metal in the period 2.
Ans:- 1. Lithium (Li)

• * An alkaline earth metal in the period 3.
Ans:- Magnesium (Mg)

• * Three nonmetallic elements in period 2.
Ans:- 1. Nitrogen (N) 
2. Oxygen (O)

🥁 Write the name and symbol of the element from the description

• * The atom has the smallest atomic mass.
Ans:- Hydrogen (H)

• * The atom has the smallest size.
Ans:- Helium (He)  

Many people would think that the answer is hydrogen but it is not. Helium is the smallest 🥁 element in the periodic table. Helium has a size of 31 pm while hydrogen has a size of 53 pm. 🎺🥁🎇

• * The most electronegative atom.
Ans:- Fluorine (F) 

• * The noble gas with the smallest atomic nucleus.        
Ans:- Helium (He)

• * The most reactive nonmetal     

 Ans:- Fluorine (F)

• * The product forms in the thermal decomposition of sugar.        
Ans:- Carbon (C)

• * The gas evolved when sodium metal reacted with ethanol.        
Ans:- Hydrogen (H)

• * The precipitate formed when barium sulphide BaS reacted with zinc sulphate ZnSO4.        
Ans:- Barium sulphate (BaSO4)

• * The reducing agent used for the reduction of copper oxide.        Ans:- Hydrogen (H)

• * The oxidizing agent used to oxidize ferrous sulphate.        
Ans:- potasium paramagnet (KMnO4)
• * Name the first artificial satellite sent by Russia into space.        
Ans:- Sputnik

• * The number of double bonds in benzene.        
Ans:- Three

• * The main component of natural gas.        
Ans:- Methane (CH4)

• * Nomenclature system based on the structure of the compounds and it was accepted all over the world.        
Ans:- International Union of pure and Applied Chemistry (IUPAC)

• * The device used for grinding an ore.        
Ans:- Grinding mill

• * The process of heating the carbonate ore to a high temperature in limited air.        
Ans:- Calcination

• * The process of heating the sulphide ore to a high temperature over the air.        
Ans:- Roasting

• * Two Highly reactive metals.        Ans:- 1. potassium K                     
               2. sodium Na

• * A common ore of aluminum.            
Ans:- Bauxite { Al2O3,H2O}

• * Compounds that are added to lower the fusion temperature of alumina.        
Ans:- Cryolite and Fluorspar

• * An alloy of copper and zinc.            
Ans:- Brass

• *A metal that forms an amphoteric oxide.            
Ans:- Aluminum (and zinc)

• * A metal that does not react with cold water but reacts with steam.
Ans: 1. Aluminium         
2. Iron        
3. zinc

• * The lens that forms a real image or virtual image depending on the position of the object.        
Ans:- A convex lens

• * Name the lens which produces magnification always less than 1.            
Ans:- A concave lens

• * Constituents of the alloy used to make a fuse wire.        
Ans:- Lead (Pb) & tin (Sn)

एक दोस्त : तुम हर शुक्रवार को अपनी बीवी से लड़ाई झगड़ा करते हो और सोमवार को उसे राजी कर लेते हो, इससे क्या फायदा होता है..?

दूसरा दोस्त : भाई किसी को बताना नहीं, 
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