Solutions of Class 10 Science Important Questions for Term 1 and Term 2 CBSE Board exam

CBSE Class 10 Science Exam 2019-20: Important questions with answers for most recent test design. Here we are giving significant solutions of important questions to the changed syllabus in CBSE Class 10 Science Exam 2019-20. Practicing these important questions and inspecting their answers will without a doubt help you plan better for the exam.

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Finding the roots of the polynomial by the complete square method

Addition subtractions multiplication and division of of polynomials

Q1 (a) List any two changes which take place when oily food get oxidized.

(b) Mention a measure which prevents or slows down its oxidation.

(a) Answer- modifications prominently occurs when food gets oxidized are (i) Bad smell (ii) Bad taste

(b) Answer- Anti-oxidants are introduced to meals which prevent it to get oxidized for instance ascorbic acid(vitamin c), vitamins A and E, vinegar also works as antioxidants as well as antifungal and antibacterial that’s why it’s frequently used in pickle and different packaged meals.

Q2.Out of the two metals P and Q, P is less reactive than Q. Suggest an activity to arrange these metals in the order of their decreasing reactivity. Support your answer with a suitable chemical equation.

Answer-Dissolving the metal Q in the salt solution of P, Q displaces P which shows that Q is more reactive than P. If we dissolve P inside the salt solution of Q, Q couldn’t get replaced by P, so Q is more reactive than P.

Q + salt solution of P ⇒P + salt solution of Q

P + salt solution of Q ⇒ No reaction

Q3.Mention the condition under which charges can move in a conductor. Name the device which is used to maintain this condition in an electric circuit.

Answer-Charges can flow if there’s a difference of electric-powered pressure or potential difference across the ends of a conductor.

Electric cell or a battery, electric generator and dynamo maintains potential differences across the conductor or in the circuit that allows the flow of charge.

Q4. YX Magnetic field lines are shown in the given diagram. A student makes a statement that magnetic field at X is stronger than at Y. Justify this statement. Also, redraw the diagram and mark the direction of magnetic field lines.

Answer-The intensity of the magnetic field lines traces is greater on the ends of the magnet so the observation of the student that the magnetic field is more potent at x in comparison to at Y is all right.

The magnetic field lines originate from the north pole and merge into the south pole, so the direction of the magnetic field might be from north to south pole as shown bellow.

Q5.Write the balanced chemical equation for the following reaction and identify the type of reaction and define it. ‘Iron III oxide reacts with Aluminium and gives molten iron and aluminum oxide’.

Answer-

$Fe_{3}O_{4}+ 2Al\Rightarrow Al_{2}O_{3}+ 2Fe$

The reaction is generally referred to as thermite for the considerable amount of heat produced. The iron produced via the reaction is molten.

Q6 Name the following :

(a) A metal which is preserved in kerosene

(b) A lustrous colored non-metal

(c) A metal which can melt while kept on the palm.

(d) A metal, which is a poor conductor of heat.

Answers-

(a) Sodium, lithium & Potassium are preserved in kerosene.

(b) Iodine &Diamond are lustrous colored non-metals.

(c) Gallium & Caesium have the lowest melting point of 29.8° and 28.5° respectively which could melt while kept on the palm.

(d) Mercury & Lead are metals which are poor conductor of heat.

Q7.An electric heater rated 800 W operates 6 h/day. Find the cost of energy to operate it for 30 days at ` 3.00 per unit.

Answer-Hours of consumtion for 30 days = 30 × 6 = 180 h
800 W = 800/1000 = 0.8 KW
Electric energy = power × Time
= 0.8 KW × 180 h
= 144 KWh ( 1KWh = 1 unit)
Cost/unit = ₹3.00
value of energy = 144 kWh × ₹3.00 / kWh
= ₹432

Q8 Draw magnetic field lines produced around a current carrying straight conductor passing through cardboard.

Answer.

Q9.How will the strength of the magnetic field change, when the point where the magnetic field is to be determined, is moved away from the straight wire carrying constant current? Justify your answer.

Answer- The direction of the magnetic field around the current carrying conductor is perpendicular to the direction of current through the conductor,the magnetic field lines produced around it can be shown by the concentric circles around it, The strength of the magnetic field decreases when the point moves away from the straight wire carrying constant current.

Q10.How many covalent bonds does ethane has ?

Answer. Ethane has 1 C-C bond and 6 C-H bonds,in total ethane has 7 covalent bonds.

Q11.In which form H† ion exists in the water ?

Answer.H⁺ions exist in the water in the form of H₃O⁺(hydronium) ions.

Q12. Write Snell’s law.

Answer. When a light ray passes from one medium to another medium the ratio between the sine of incident angle and refracted angle is constant.

sin i/sin r = Constant, where i is incident angle and r is refracted angle

Q13.Which liquid fills the space between eye lenses and retina.

Answer.The space between eye lenses and retina is called the vitreous chamber which is filled with a transparent jelly-like fluid vitreous humor.

Q14.What is electromagnetic induction?

Answer. When a conductor moves in a magnetic field,a voltage is produced across it,it is a phenomenon used in the dynamo in the production of electricity. First time it was discovered by Faraday.

Q15.State the modern periodic law.

Answer. Properties of the elements are the periodic function of their atomic number,this is the law modern periodic table is based upon.

Q16. What is short-circuiting?

Answer. When two electrical wires come in contact with each other, their net resistance become law and high current flows through the circuit, due to high current, excess heat produced blow the circuit. The path of the circuit becomes shorter that’s why this problem is given the name short circuit.

Q17.What is the power of bulb rated at 2.5 volts,500 mA?

Answer.As we know P = V × I, where P=Power,V =Voltage, I=Current

V=2.5v, I=500 mA= 500/1000=0.5 A (1A =1000mA)

P = 2.5v × 0.5A = 1.25W

Therefore the power of the bulb =1.25W

Q18.An object is kept at a distance of 5 cm in front of a convex mirror of focal length 10 cm.Give the position,magnification and nature of the image formed.

Answer. the distance of the object (u)= –5 cm, focal length(f) = +10 cm(Focal point of convex mirror lies behind the mirror), distance of the image formed=v =?

Applying the mirror formula,we have

${\color{DarkBlue} \mathbf{\frac{1}{f}= \frac{1}{v}+ \frac{1}{u}}}$

${\color{DarkBlue} \mathbf{\frac{1}{10}= \frac{1}{v}+ \frac{1}{-5}}}$

${\color{DarkBlue} \mathbf{\frac{1}{v}= \frac{1}{10}+ \frac{1}{5}}}$

${\color{DarkBlue} \mathbf{\frac{1}{v}=\frac{3}{10}}}$

${\color{DarkBlue} \mathbf{v=\frac{10}{3}=3.33}}$

The position of image formed is 3.33 cm behind the mirror.

Q19.What is meant by the magnetic field lines ? Draw the pattern of the magnetic field lines due to a current-carrying circular loop of wire.

Answer. Magnetic field lines show the direction and strength of the magnetic field around a magnet,if a small compass is used to map out across a magnet the needle indicating north pole point out the direction of the magnetic field, it could be seen that these field lines originate from the north pole and merge into the south pole ,we can observe these field lines if we place a bar magnet on a plane of paper containing iron dust, the iron dust aligned into the form of the curved lines, these lines are known as magnetic field lines. Field lines show the direction and intensity of the magnetic field.

Q20.What is the chemical formula of Plaster of Paris? How is it prepared? State the common and the chemical names of the compound formed when Plaster of Paris is mixed with water.

Answer.the chemical formula of Plaster of Paris

${\color{DarkBlue} \mathbf{CaSO_{4}.\frac{1}{2}H_{2}O}}$

Plaster of Paris is prepared by heating gypsum up to 300°c, lossing ${\color{DarkBlue} \mathbf{1\frac{1}{2}}}$ molecule of water it forms Plaster of Paris.

${\color{DarkBlue} \mathbf{CaSO_{4}.2H_{2}O \xrightarrow[Heat]{300^{\circ}C}\; \; CaSO_{4}.\frac{1}{2}H_{2}O}}$

Giypsum POP

When POP is mixed with water it is crystallized to form Gypsum which is a hard substance.

${\color{DarkBlue} \mathbf{CaSO_{4}.\frac{1}{2}H_{2}O +1\frac{1}{2}H_{2}O\rightarrow CaSO_{4}.2H_{2}O}}$

POP Gypsum

The common name of CaSO4.2H2O is Gypsum and its chemica name is Calcium Sulphate Dihydrate

Q21.What is the Chlor-alkali process?Why is it so called?

Answer. The electrolysis of an aqueous solution of sodium chloride is known as Chlor-alkali process, it is called Chlor-alkali process because the products formed during this process are NaOH(Caustic soda) an alkali used in soap industry and chlorine(Chlor) gas used as antiseptic for improving quality of water.The hydrogen gas is also produced in this process.

${\color{DarkBlue} \mathbf{2NaCl\left ( aq \right ) +2H_{2}O\left ( l \right )\underset{\mathbf{Electrolysis}}{\rightarrow} 2NaOH + Cl_{2}\left ( g \right )+H_{2}\left ( g \right )}}$

Q22.How does the electronic configuration of an atom related to its position in the modern periodic table ?

Answer.Electronic configuration of an atom determines the valancy of element ,the valance e’s of atom shows the last digit of group number and number of orbital shows the period of atom.As an example Na(11)-2,8,1 Cl-2,8,7, the group number of sodium is one and its period is 3 and group number of chlorine is 17 and its period is 3.

Q23.A bulb is rated at 5.0 V-100mA; calculate its (a) Power, and (b) Resistance.

Answer. Power(P) = Volage(V) × Electric Current(I)

V = 5.0V, I = 100 mA= 100/1000 =0.10A

P= V × I = 5.0 × 0.10 = 0.50W

Voltage(V) = I × R(Ohm’s law)

R = V/I = 5.0/0.10 =50Ω

Therefore the power of bulb is 0.50W and its resistance is 50Ω.

Q24. Write any two factors on which strength of two induced current depends.

Answer. The induced current depends on the following factors.

The strength of magnetic field.
Motion of the conductor.

Q26.Give reasons for the following;

(a)Metals conduct electricity .

(b)Metals generally do not form compounds with hydrogen.

(c)Nitrogen gas is used to preserve food.

Answer.(a) Metals conduct electricity because it contains free electrons in the gaps between its atoms, these free electrons exist only in metals because e’s in it are not bound by any chemical bond like a covalent or ionic bond, so these e’s can move freely within the metal.When an electric potential difference is generated in its both ends these e’s moves from one end to another end generating a current through the conductor.

(b)Metals and Hydrogen both are positively charged ,so neither they can form ionic bond nor a covalent bond in the formation of the compound,but few of metals like Na,K,mg and Ca are most reactive so these atoms forces hydrogen to form their hydride.

(c) In the packaging material nitrogen gas is filled because it doesn’t react with oily substance available in the food moreover, it displaces oxygen available inside the packet and prevents the food to be oxidized.

NCERT Solutions of Science and Maths for Class 9,10,11 and 12

NCERT Solutions for class 9 maths

Chapter 1- Number System	Chapter 9-Areas of parallelogram and triangles
Chapter 2-Polynomial	Chapter 10-Circles
Chapter 3- Coordinate Geometry	Chapter 11-Construction
Chapter 4- Linear equations in two variables	Chapter 12-Heron’s Formula
Chapter 5- Introduction to Euclid’s Geometry	Chapter 13-Surface Areas and Volumes
Chapter 6-Lines and Angles	Chapter 14-Statistics
Chapter 7-Triangles	Chapter 15-Probability
Chapter 8- Quadrilateral

NCERT Solutions for class 9 science

Chapter 1-Matter in our surroundings	Chapter 9- Force and laws of motion
Chapter 2-Is matter around us pure?	Chapter 10- Gravitation
Chapter3- Atoms and Molecules	Chapter 11- Work and Energy
Chapter 4-Structure of the Atom	Chapter 12- Sound
Chapter 5-Fundamental unit of life	Chapter 13-Why do we fall ill ?
Chapter 6- Tissues	Chapter 14- Natural Resources
Chapter 7- Diversity in living organism	Chapter 15-Improvement in food resources
Chapter 8- Motion	Last years question papers & sample papers

NCERT Solutions for class 10 maths

Chapter 1-Real number	Chapter 9-Some application of Trigonometry
Chapter 2-Polynomial	Chapter 10-Circles
Chapter 3-Linear equations	Chapter 11- Construction
Chapter 4- Quadratic equations	Chapter 12-Area related to circle
Chapter 5-Arithmetic Progression	Chapter 13-Surface areas and Volume
Chapter 6-Triangle	Chapter 14-Statistics
Chapter 7- Co-ordinate geometry	Chapter 15-Probability
Chapter 8-Trigonometry

CBSE Class 10-Question paper of maths 2021 with solutions

CBSE Class 10-Half yearly question paper of maths 2020 with solutions

CBSE Class 10 -Question paper of maths 2020 with solutions

CBSE Class 10-Question paper of maths 2019 with solutions

NCERT Solutions for Class 10 Science

Chapter 1- Chemical reactions and equations	Chapter 9- Heredity and Evolution
Chapter 2- Acid, Base and Salt	Chapter 10- Light reflection and refraction
Chapter 3- Metals and Non-Metals	Chapter 11- Human eye and colorful world
Chapter 4- Carbon and its Compounds	Chapter 12- Electricity
Chapter 5-Periodic classification of elements	Chapter 13-Magnetic effect of electric current
Chapter 6- Life Process	Chapter 14-Sources of Energy
Chapter 7-Control and Coordination	Chapter 15-Environment
Chapter 8- How do organisms reproduce?	Chapter 16-Management of Natural Resources

NCERT Solutions for class 11 maths

Chapter 1-Sets	Chapter 9-Sequences and Series
Chapter 2- Relations and functions	Chapter 10- Straight Lines
Chapter 3- Trigonometry	Chapter 11-Conic Sections
Chapter 4-Principle of mathematical induction	Chapter 12-Introduction to three Dimensional Geometry
Chapter 5-Complex numbers	Chapter 13- Limits and Derivatives
Chapter 6- Linear Inequalities	Chapter 14-Mathematical Reasoning
Chapter 7- Permutations and Combinations	Chapter 15- Statistics
Chapter 8- Binomial Theorem	Chapter 16- Probability

CBSE Class 11-Question paper of maths 2015

CBSE Class 11 – Second unit test of maths 2021 with solutions

NCERT solutions for class 12 maths

Chapter 1-Relations and Functions	Chapter 9-Differential Equations
Chapter 2-Inverse Trigonometric Functions	Chapter 10-Vector Algebra
Chapter 3-Matrices	Chapter 11 – Three Dimensional Geometry
Chapter 4-Determinants	Chapter 12-Linear Programming
Chapter 5- Continuity and Differentiability	Chapter 13-Probability
Chapter 6- Application of Derivation	CBSE Class 12- Question paper of maths 2021 with solutions
Chapter 7- Integrals
Chapter 8-Application of Integrals