Class 11/10/9/8 - Chemistry - Uses of Gases (Worksheet) (#eduvictors)(#cbsenotes)

Uses of Gases 

(Worksheet)

Fill the blanks:

1. The gas that can be used to fill party balloons is _______.

2. The gas that is used to make flash light is _______ .

3. The gas widely used in advertisement signs is _______.

4. The gas present in tungsten bulb is _______.

5. The gas present in the universe is _______.

CLASS 10 - CHEMISTRY - CHEMICAL REACTIONS AND EQUATIONS - Chapter Summary Notes (#eduvictors)(#cbsenotes)

CHEMICAL REACTIONS AND EQUATIONS

Chapter Summary Notes

1. Chemical reaction — 

Chemical changes or chemical reactions are the changes in which one or more new substances are formed.

2. Chemical Equations – 

Representation of a chemical reaction in terms of symbols and formulae of the reactants and products is known as a chemical equation.

3. Balanced Chemical equations – 

The chemical equation in which the no. of atoms of different elements is same on both sides of the arrow is called balanced chemical equation.

4. The chemical reactions can be classified into different types such as—

a. Combination reaction.
b. Decomposition reaction.
c. Displacement reaction.
 d. Double Displacement reaction.
i. Precipitation reaction
ii. Neutralization reaction
e. Redox reaction

CBSE Class 10 - Chemistry - Ch5 - Periodic Classification Of Elements (Concept Points) (#cbseNotes)

PERIODIC CLASSIFICATION OF ELEMENTS (Concept Points)

Modern Periodic Table
credits: By Mbenzdabest (Own work) [CC BY-SA 4.0 ],
via Wikimedia Commons

1. Early chemists classified elements as metals and non-metals on the basis of a set of physical and chemical properties.

2. Dobereiner classified elements on the basis of “Law of Triads” which states that “atomic mass of the middle element of a triad is almost the arithmetic mean of the other two elements”.


3. A triad of elements is a group of three elements arranged in the order of increasing atomic masses, such that a group of such elements have similar physical and chemical properties.


4. Newland classified elements on the basis of “Law of Octaves” stated by him. According to
this law :
“When the elements are arranged in the order of increasing atomic mass, the properties of the eighth element (starting from a given element) are a repetition of the properties of the first element.”

CBSE Class 10 - Chemistry - Chapter 4 - Carbon and its Compounds - Important Points To Memorise (#cbsenotes)

Carbon and its Compounds 

Important Points To Memorise

1. Carbon forms a large variety of compounds because of its tetra-valency and the property of catenation.


2. Hydrocarbons are the compounds of carbon and hydrogen.


3. Hydrocarbons are of two types – saturated hydrocarbons (alkanes) and unsaturated hydrocarbons (alkenes and alkynes)

CBSE Class 10 -Chemistry - Metals and Non-Metals (Short Q and A)(#cbseNotes)

Metals and Non-Metals (Short Q and A)

Q1: Define Element.

Answer: An element is a pure substance which is made up of same kind of atom which differs from their physical and chemical properties.


Q2: How many elements are known so far? How many of them are naturally occurring?

Answer: 118 under which 92 are naturally occurring.


Q3: Give examples of the most abundant elements.

Answer: Aluminium ( the most) and Iron


Q4: Which is the most abundant non-metal?

Answer: Oxygen (O)


Q5: Give examples of the least reactive metals.

Answer:
• Gold
• Silver
• Platinum

CBSE Class 10 - Chemistry - Metals and Non-Metals - Alloys Their Compositions and Uses (#cbseNotes)

Alloys - Compositions, Properties and Uses

① Steel
Components: Iron, Carbon

Properties: Hard and Strong

Uses:
- Construction of buildings and bridges,
- manufacture of ships
- manufacture of spare parts for automobiles

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CBSE Class 10 - Chemistry - Acids and Bases - pH of common Acids, Bases and Salts (#cbseNotes)

pH of common Acids, Bases and Salts

The acidity of an aqueous solution relies on the concentration of hydronium ions, [H₃O⁺]. For various products (acids, bases and salts), the magnitude of this concentration varies and pH scale is used conveniently. The pH of a solution is defined as the negative base-10 logarithm of the hydronium ion concentration (in mol/L). Here follows a partial list of pH of common acids, bases and salts.

Solution	PH range
HCL	1.0 - 2.0
Gastric Juices	1.4 - 2.0
Lemon Juice	2.0- 3.0
Vinegar	4.0
Tomato Juice (Oxalic Acid)	4.1
Coffee	5.0
Milk (Lactic Acid)	6.5

CBSE Class 10 - Chemistry - 23 HOTS Questions on Chemical Reactions You Must Know - Q and A (#cbsenotes)

23 HOTS Questions on Chemical Reactions You Must Know

Class 10 - Chemistry - Q & A

Q1: A white coloured water insoluble substance X on reacting with dilute H₂SO₄ released a colourless and odourless gas accompanied by brisk effervescence. When the gas was passed through water, the solution obtained turned blue litmus red. On bubbling the gas through lime water, it initially became milky and milkiness disappeared when the gas was passed in excess. Identify the substance X‘. Write its chemical equations of the reactions involved.

Answer: Calcium carbonate on reacting with dilute sulphuric acid releases a colourless and odourless gas carbon dioxide accompanied  by brisk effervescence.

The chemical equation for this reaction is
CaCO₃ + H₂SO₄ → CaSO₄ + H₂O + CO₂

Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l)
milky

CO₂ (g) + CaCO₃ (s) + H₂O (l) ⇌ Ca(HCO₃)₂ (aq)
(colourless)



Q2: Ahmad took a magnesium ribbon (cleaned) and burned it on a flame. The white powder formed was taken in a test tube and water was added to it. He then tested the solution formed with red and blue litmus paper. What change was seen? Why?


Answer:
⒜ Red litmus paper turned blue.
⒝ Blue litmus paper remained blue.

This is because the magnesium ribbon on burning in air forms the white magnesium oxide. MgO when dissolves in water, it forms magnesium hydroxide, which is basic in nature.

2Mg + O₂ → 2MgO

MgO + H₂O → Mg(OH)₂ (aq) + H₂(g)

CBSE Class 10 Chemistry - CH2 Acids and Bases - Very Short Questions and Answers (#cbsenotes)

Acids and Bases  

Very Short Questions and Answers

Class 10 Science - Chemistry

Q1: What is an acid?

Answer: Acid is a compound which yields hydrogen ions (H⁺) or Hydronium (H₃O⁺) ions , when dissolved in water.


Q2: What is the pH value of acids?

Answer: Less than 7 (i.e. 0 to < 7)


Q3: What is the taste of acids?

Answer: Sour


Q4: What happens to blue litmus paper when it comes in contact with acid solution?

Answer: It turns into red.


Q5: On the basis of origin, how acids are classified as?

Answer: Organic acids and Mineral acids.

CBSE Class 8/10 - Metals vs Non-Metals (Comparison) (#cbseNotes)

Metals vs Non-Metals

Physical Properties Comparison

Property	Metals	Non Metals
Physical State	Most metals are solids at room temperature except mercury which is a liquid. Gallium and Cesium also changes into liquid at slightly above room temperature.	Non Metals exist in all states. Eleven are gases, bromine is liquid while others are solids.
Melting and Boiling Point	Generally have high melting and boiling points. (Exceptions are Gallium, Mercury, Sodium and Potassium.)	Generally they have low melting and boiling points. Exceptions are: Carbon, Boron and Silicon.
Density	They have high density except Sodium and potassium.	Low denisty (Diamond is an exception.)
Lusture	Metals shine and are lustrous.	Non-metalls appear dull. (Exceptions are Diamond, graphite and iodine.)

CBSE Class 10 - Science - Four New Elements Added In Periodic Table

Four New Elements Added In 

Periodic Table

Time to update Chemistry Textbooks. On December 30, IUPAC completes the verification of discoveries of four new chemical elements. It completes the 7 periodic row.

The atomic numbers of these four new elements are 113, 115, 117 and 118. Soon the new names will be given to these elements. At present these elements have temporary names i.e.

Ununtrium 113, 
Ununpentium 115, 
Ununseptium 117, 
Ununoctium 118 

CBSE Class 10 Science CHEMICAL REACTIONS AND EQUATIONS - Board Questions (2008-2014) and Answers

CHEMICAL REACTIONS AND EQUATIONS

Board Questions (2008-2014) and Answers

Q1(2008): What happens chemically when quick lime is added to water?

Answer: Quick lime is CaO which reacts vigorously with water to produce slaked lime (calcium hydroxide) releasing a large amount of heat.

                           CaO(s) + H₂O(l) → Ca(OH)₂(aq)

Q2: A student burns magnesium ribbon in the lab and observes a white powder falling on the table. What type of reaction has taken place and name the white powder?

Answer: It is a chemical reaction. The white powder formed is magnesium oxide (MgO).

Q3: What are the essentials of a chemical reaction?

Answer:

• It should be balanced and confirm to the law of conservation of matter
• It should be molecular
• It must refer to an actual chemical equation

Q4: How will you test for the gas which is liberated when hydrochloric acid reacts with an active metal?

Answer: When a burning match stick is brought near the mouth of the test tube in which reaction is taking place, it will burn with popping sound. It detects the presence of hydrogen (H₂) gas.

Q5: What change in colour is observed when white silver chloride is left exposed to sunlight? What type of chemical reaction is this?

Answer: White silver chloride turns grey in sunlight. This is due to the decomposition of silver chloride into silver and chlorine by light.It is a photo-chemical decomposition reaction.

                2AgCl(s) —^Sunlight—→ 2Ag(s) + Cl₂(g)

Q6: Why is respiration considered as exothermic process?

Answer: In respiration heat is released so it is termed as an exothermic reaction.

                   C₆H₁₂O₆ + 6O₂ —→ 6CO₂ + 6H₂O + energy

Q7(2010):What is meant by skeletal equation?

Answer: The equation which is unbalanced because the mass is not the same on both sides of the equation, is a skeletal chemical equation for a reaction.

During exam, try to write chemical equations and chemical formulae in your answers wherever possible. It enhances visibility and gives you more scores.

Q8: Identify the type of reaction in the following example:

Na₂SO₄(aq) + BaCl₂(aq) —→ BaSO₄(s) + 2NaCl(aq)

Answer: A double displacement reaction.

Q9: Why are bags of chips flushed with nitrogen gas?

Answer: Chips manufacturers usually flush bags of chips with gas such as nitrogen to prevent the chips from getting oxidised.

Q10 : What is precipitation reaction?

CBSE Class 10 - Science - CH2 - Acids, Bases and Salts (Worksheet)

Acids, Bases and Salts

credits:clker.com

Worksheet

Fill in the Blanks

1. Blue litmus changes into red colour in the presence of_______.

2. The acid present in lemon juice is _______.

3. Red litmus changes into blue colour in the presence of ______.

4. The chemical name of Plaster of Paris is ___________ and its chemical formula is ____________.

5. Methyl orange gives __________ in basic medium while phenolphthalein gives _______.

6. Example for strong acid is ________.

7. Example for weak acid is ________

8. Example for strong base is_______.

9. Example for weak base is ____________

CBSE Class 10 - Science - CH2 - Acids, Bases and Salts (MCQs)

Acids, Bases and Salts

credits:clker.com

MCQs

Q1: The most commonly used indicator in laboratory is
(a) Methyl Orange
(b) Litmus
(c) Phenolphtalein
(d) Universal Indicator

Q2: Which gas is released when a metal reacts with an acid?

(a) Cl₂

(b) O₂
(c) H₂
(d) SO₂


Q3: The strength of acid depends upon

(a) density of the acid
(b) oxygen atoms present
(c) number of hydrogen atoms present in the molecule
(d) concentration of H+ ions furnished by the acid


Q4: Which statement is incorrect?

(a) Acids have pH more than 7
(b) Acids give H⁺ ions in water
(c) Acid conduct electricity in aqueous solution
(d) Acids turn blue litmus red.


Q5: Which of the following substance is antacid?

CBSE Class 10 - Science - CH3 - Metals and Non-Metals

Metals and Non-Metals

Q & A

Q1: List any five physical properties of metals.

Answer: Physical properties of metals are:

1. Metals are usually hard (exceptions are: sodium and potassium).
2. These are sonorous.
3. These are lustrous.
4. Metals exhibit malleability and ductility.
5. Mostly they are solids (exception is mercury)
6. They exhibit high tensile strength.
7. These have high densities.

Q2: Are metals electronegative or electropositive?

Answer: Metals are electropositive i,e. they form cations by loosing electrons.

Q3: Define Malleability.

Answer: Malleability is the property of a metal, by which it can be beaten into thin sheets.

Q4: Name a metal which can be cut with a knife?

Answer: Sodium

CBSE Class 10 - Science - CHEMICAL REACTIONS AND EQUATIONS (MCQs)

CHEMICAL REACTIONS AND EQUATIONS

MCQs

Q1: Which of the following is not a decomposition reaction?

(a) CaCO₃ → CaO + CO₂
(b) H₂ + Cl₂ → 2HCl
(c) H₂CO₃ → H₂O + CO₂
(d) 2KClO₃ → 2KCl + 3O₂

Q2: Which of the following is not an oxidising agent?

(a) Oxygen
(b) Conc. Sulphuric acid
(c) Chlorine
(d) Hydrogen


Q3: The oxidation reaction which produces heat and light is

(a) endothermic
(b) photochemical
(c) combustion
(d) exothermic

CBSE Class 10 - Science - CH 16 - Management of Natural Resources (Q and A)

Management of Natural Resources

Why do we need to use our resources carefully?

Q & A

Q1(CBSE 2011): What is coliform bacteria? What does its presence in water indicate?

Answer: Coliform is a group of bacteria which is found in human intestines. Its presence in water indicates contamination by disease-causing microbes. Its high presence in rivers and ponds elevates the risks of water borne diseases like gastroenteritis.

Q2(CBSE 2011): State two reasons of launching "Ganga Action Plan". Which bacteria was found in Ganga water indicating contamination?

CBSE Class 10 - CH4 - Carbon and Its Compounds (MCQs)

Carbon and Its Compounds

(MCQs)

Q1: Which of the following is an odd compound?

(a) Ethene
(b) Ethane
(c) Propene
(d) Acetylene

CBSE Class 10 - Science - CH5 - Periodic Classification of Elements (MCQs)

Periodic Classification of Elements

Circular Periodic Table
credits:wpclipart

MCQs

Q1(NCERT): Which of the following statements is not a correct statement about the trends when going from left to right across the periods of periodic Table.

(a) The elements become less metallic in nature.
(b) The number of valence electrons increases.
(c) The atoms lose their electrons more easily.
(d) The oxides become more acidic.

CBSE Class 9/10 - Science - All about Names of the Chemical Elements

All about Names of the Chemical Elements

1. There are 115 chemical elements known today to the world. Only 90 are found in nature and the rest are artificially created.

2. A good number of elements are named after human beings and mythological figures.