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 6 Science CH 9 The Living Organisms and Their Surroundings (MCQs)

The Living Organisms and Their Surroundings

MCQs based Class 6 NCERT Chapter 9 

Habitats

Q1: In the sea, plants and animals are surrounded by _________ water.

(a) fresh
(b) saline
(c) acidic
(d) marshy

Q2: The surroundings where organisms live is called a _______.

(a) habitat
(b) habit
(c) dwellings
(d) adaptation

Q3: In Cactus plants, the leafy kike structure in actual is a ______.

(a) leaf
(b) root
(c) flower
(d) stem

Q4: Sea animals like dolphins and whales breathe through ______.

(a) nose
(b) gills
(c) blow holes
(d) fins

Q5: Breathing activity is a part of which of the following bio-chemical process?

(a) photosynthesis
(b) respiration
(c) digestion
(d) excretion

CBSE Class 12 - Business Studies - CH9 - FINANCIAL MANAGEMENT (V Short Q and A)

FINANCIAL MANAGEMENT

Very Short Q & A

Q1: What do you mean by business finance?

Answer: The money required for carrying out business activities is called business finance.

Q2: What is Financial Management?

Answer: Financial Management is group of activities that are associated with optimal procurement as well as usage of finance.

Q3: Name the cheapest source of finance to a company.

Answer: Debt capital

Q4: What is wealth maximization concept?

Answer: It refers to primary aim of finance management i.e. to maximize shareholders’ wealth.

Q5: What is Financial Planning?

Answer: Financial Planning refers to determination of firms financial objectives, financial policies and procedures.

CBSE Class 10 Maths CH6 Triangles (Important Points You must Know)

Triangles: Important Points You must Know

1. Two figures are said to be similar if and only if they have same shape but not necessarily of same size.

2. All the congruent figures are similar but the converse is not true.

3. Two polygons of the same number of sides are similar if and only if
   (i) their corresponding angles are equal
   (ii) their corresponding sides are in proportion (same ratio).
 
4. Basic Proportionality Theorem (Thales Theorem):
   If a line is drawn parallel to one side of a triangle to intersect the other two sides in distinct points, then the other two sides are divided in the same ratio.(see figure above)
 

5. Converse of Basic Proportionality Theorem: If a line divides any two sides of a triangle in the same ratio, then the line is parallel to third side.

6. Similar Triangles: Two triangles are similar if and only if
   i.  their corresponding angles are equal i.e. they are equi-angular and
   ii. their corresponding sides are in the same ratio.
 
7. Criteria for establishing similarity of two triangles:
   i.   AA (or AAA) criterion of similarity
   ii.  SSS criterion
   iii. SAS criterion
   iv.  Altitude of right angle triangles

CBSE Class 6 Science CH13: Fun With Magnets (MCQs)

Fun With Magnets

Magnets come in various shapes. Can you name those shown?
(Answers given below?)

MCQs

Q1: In a bar magnet, magnetic power is

(a) more that both ends of the magnet.
(b) more in the middle of the magnet.
(c) is same through the magnet.
(d) none of these

Q2(NCERT): A bar magnet is immersed in a heap of iron filings and pulled out. The amount of iron filling clinging to the

(a) North pole is almost equal to the south pole.
(b) North pole is much more than the south pole.
(c) North pole is much less than the south pole.
(d) Magnet will be same all along its length.

Q3: When a magnet is suspended freely in air with the help of string, it aligns itself in _________ direction.

(a) South-West
(b) North-East
(c) East-West
(d) North-South

Q5: Which of the following is a non-magnetic material?

CBSE Class 12 Business Studies - CH 8 - Controlling (V Short Q and A)

Controlling

Very Short Q & A

Q1: Define Controlling.

Answer: It is a process of comparing actual performance with standards and finding deviations if any and taking corrective action.

Q2: Both quantitative and qualitative benchmarks are set to measure actual performance. Which element of controlling is referred here?

Answer: Comparing actual performance with standards.

Q3: What are the characteristics of controlling that are also possessed by planning?

Answer: Unity, continuity, flexibility and pervasiveness.

Q4: Is controlling a one-stop process or continuous process?

Answer: Controlling is a continuous process. It involves constant revision and analysis of standards resulting from the deviations between actual and planned performance.

Q5: What are standards?

Answer: Standards are the norms against which the performance is measured to find out the result.

Q6: Which two standards do you suggest for the production department?

Answer:
   i. qualitative
   ii. quantitative

Q7: List any three advantages of controlling.

CBSE Class 6 Science CH14 Water (MCQs)

Water

MCQs

Q1: The process of changing water into ice is called __________.

(a) sublimation
(b) evaporation
(c) freezing
(d) precipitation

Q2: The process of falling down of water in the form of rain, snow or hail is called _________.

(a) sublimation
(b) evaporation
(c) condensation
(d) precipitation

Q3: How much water is lost approximately through transpiration by wheat plants that give us one kilogram of wheat?

(a) 5 litres
(b) 50 litres
(c) 500 litres
(d) 5000 litres

Q4: Which of the following will lead to a reduction in the availability of groundwater?

(a) plantation
(b) rainwater harvesting
(c) constructing more lakes
(d) building concrete roads

Q5: When ice water is poured into a glass, tiny water droplets of water appear on the outside of glass due to _________.

CBSE Class 7 Science CH1 - Nutrition In Plants (MCQs)

Nutrition In Plants

Pitcher Plant: A carnivorous plant
image credits: wikipedia

MCQs
Q1: Which of the following is not an end product of photosynthesis?

(a) Oxygen
(b) Carbon dioxide
(c) Water
(d) Glucose

Q2: Which of the following organisms gets its food from dead and decaying matter?

(a) Algae
(b) Fungi
(c) Amoeba
(d) Insectivorous plants

Q3: Which of the following are autotrophs?

(a) all plants
(b) Green plants
(c) All animals
(d) Unicellular organisms

Q4: Photosynthesis is not possible in the absence of ________.

(a) Guard cells
(b) Chlorophyll
(c) Vacuole
(d) Space between cells

Q5: The associations of organism where they live together and share shelter and nutrients is known as ___________.

CBSE Class 12 Business Studies CH 7 - Directing (V Short Q and A)

Directing

V Short Q & A

Q1: Define directing.

Answer: Directing refers to the process of instructing, guiding, counselling, motivating and leading people in the organisation to achieve its objectives.

Q2: List any two essential elements of Direction.

Answer:
   1. Supervision
   2. Communication
   3. Leadership
   4. Motivation

Q3: What does Unity of Direction signify?

Answer: Unity of direction signifies the existence of only one head and one plan for a group of activities which have the same objective. It results from a sound organisation structure.

Q4: Every manager from the top executive to superior performs the function of directing.  Which characteristic of directing is referred to here?

Answer: It refers that directing takes place every level of management.

Q5: It takes place throughout the life of the organization irrespective of people occupying managerial positions. Mention the characteristic of directing high lighted here 

Answer: Directing is pervasive and it is a continuing process.

Q6: List any three factors of effective supervision.

Answer:
   1. Skills and abilities
   2. Leadership position
   3. Nature of supervision
   4. Group cohesiveness

Q7: "To oversee the subordinates at work"  Which element of directing is referred to?

Answer: Supervision

Q8: Is directing is a pervasive function of management?

Answer: Yes, as every manager from the top executive to subordinates performs it.

Q9: Which element of directing help in inspiring subordinates to give their best to the organization?

CBSE Class 7 Science CH10 Respiration In Organisms (MCQs)

Respiration In Organisms

Human Respiratory System
image credits: wikipedia

MCQs

Q1: Breathing is a ________ process while respiration is a _______ process.

(a) physical, chemical
(b) chemical, physical
(c) physical, physical
(d) chemical, chemical

Q2: Organisms which respire in absence of air are called _________. 

(a) microbes
(b) anaerobes
(c) aerobes
(d) none of these

Q3: Plants breathe through tiny pores in the leaves called ________.

(a) leaf blade
(b) trachea
(c) pores
(d) stomata

Q4: In earthworm, the exchange of gases occurs through ________.

(a) lungs
(b) gills
(c) moist skin
(d) tracheae

Q5: During Inspiration or Inhalation, inside lungs