Skip to main content

CBSE Class 7th Chapter: Science HOTs Questions


CBSE Class 7th Chapter: Physical and Chemical Change HOTs Questions
1. Why gas is released after opening Soda Water bottle?

Ans: Soda water bottle contain CO2 gas that released after opening the soda water bottle.

2. Why it is advised that spoon should not be placed in pickle Jar?

Ans: Spoon is made up of metal that react with acid present in pickle and form another salt and spoil the pickle .Hence it is advised that spoon should not be placed in pickle Jar

3. Why does apple Slice got brown color if kept in air for long time?

Ans: Apple Slice got brown color if kept in air for long time because it  react with oxygen and form layer of oxide  which spoil the apple .This is called rancidity.

4. How is Scratch resistant material is made?

Ans: Scratch resistant material is made by mixing two or more metal called Alloy like steel.

CBSE Class 7th Chapter: Electric Current and Circuit: HOTs Questions

1. Why does electric current show magnetic effect?

When electric current flows through a conductor, electrons move by spinning and orbiting nucleus. This motion of electrons produces magnetic effect. As Ampere suggested, a magnetic field is produced whenever an electrical charge is in motion.

2. Does magnetic field always surrounds a current carrying conductor? What is its cause?

Yes. Magnetic field always surrounds a current carrying conductor due to electron move through a conductor by magnetic field always surrounds a current carrying conductor

3. Why are fuse wire not used in circuit containing electric cell?
Ans: Fuse wire is used to prevent sudden excess flow of current. Cell provide current of fix magnitude So fuse wire are  not used in circuit containing electric cell

4. Why does electric current show heating effect?

When electric current flows through a conductor, a part of electrical energy get converted into heat energy due resistance offered to electron.

 CBSE Class 7th Chapter: Transportation and Excretion: HOTs Questions

1. Why is colour of human blood?

Ans: The colour of human is blood due colour pigment haemoglobin that help to carry oxygen .

2. What do you mean by serum and serum protein?

Ans: The coloured liquid part present in Plasma is called Serum. It helps in clotting bloods. Protein present in plasma is called serum protein.           

3. Why is urinary bladder absent in snake, bird etc?

The cloaca is a common chamber that separately receives products of the kidneys, large intestine, and reproductive tracts so urinary bladder absent in snake, bird etc

4. How transportation helpful in ascent of sap in plants?

The movement of water molecules and minerals against the gravity force with the help of Xylem tissue is known as Ascent of Sap. In transpiration plant loose water in the form of water vapour. Hence the loss of water due to transpiration speed up ascent of sap.

5. What is difference in mode of transportation in xylem and phloem?

And: Phloem and xylem are complex tissues that perform transportation. Xylem transport water and mineral from root to leaves and Phloem transport prepared food fron leaves to all parts of plants.

CBSE Class 7th Chapter: Natural Phenomena: wind, Rain and Light : HOTs Questions

1. Why are people advised not to stand near fast moving train?

Ans: When train moves with high speed it creates region of lower pressure . This low pressure  push man towards the train

2. Why are holes made in huge hoardings? Explain their usefulness.

Ans:  Holes are made in huge hoardings to reduce air pressure causing it to flutter or blown away.

3. in winter regions near, why does wind blow from land to sea?

Ans:. In winter the sea become warmer quickly than the land. So In winter monsoon blows from land to sea

4. Why are things colorful in appearance?

Ans: The colour of object is colour that is reflected. Thus different color makes things colorful.

Comments

CBSE ADDA :By Jsunil Sir : Your Ultimate Destination for CBSE Exam Preparation and Academic Insights

Class 10 Chapter 02 Acid Bases and Salts NCERT Activity Explanation

NCERT Activity Chapter 02 Acid Bases and Salt Class 10 Chemistry Activity 2.1 Indicator Acid Base Red litmus No Change Blue Blue Litmus Red No change Phenolphthalein Colourless Pink Methyl Orange Pink   Yellow Indictors are substance which change colour in acidic or basic media. Activity 2.2 There are some substances whose odour changes in in acidic or basic media. These are called olfactory indicators. Like onion vanilla, onion and clove. These changes smell in basic solution. Activity 2.3 Take about 5 mL of dilute sulphuric acid in a test tube and add few pieces of zinc granules to it. => You will observe bubbles of hydrogen gas on the surface of zinc granules. Zn + H2SO4 --> ZnSO4 + H2 => Pass the Hydrogen gas through the soap solution. Bubbles formed in the soap solution as Hydrogen gas it does not get dissolved in it

Living science ratna sagar class 6 solutions

Ratna sagar living science 6 answers by jsunil. Class6 Living science solution Term-1 Living Science Solution chapter-1 Source of food Download File Living Science Solution chapter-2 Component of food Download File Living Science Solution chapter-3 Fibre to fabric Download File Living Science Sol ch-4 Sorting of material into group Download File Living Science Soln ch-5 Separation of substance Download File Living Science Solution chapter-6 Change around Us Download File Living Science Solution ch-7 Living and Non Living Download File Living Science Solution ch-8 Getting to Know Plants Download File Living Science Sol ch-9 The Body and Its movements Download File Visit given link for full answer Class6 Living science solution Term-II

Class 10 Metal and Non MetalsChapter 03 NCERT Activity Solutions

X Class 10 NCERT Activity Explanation Class 10 Metals and Non Metals Activity 3.1 Page No. 37 Take samples of iron, copper, aluminium and magnesium. Note the appearance of each sample. They have a shining surface. Clean the surface of each sample by rubbing them with sand paper and note their appearance again. They become more shiny. => Freshly cut Metal have shiny surface Activity 3.2 Page No. 37 Take small pieces of iron, copper, aluminium, and magnesium. Try to cut these metals with a sharp knife and note your observations. They are very hard to cut. Hold a piece of sodium metal with a pair of tongs and try to cut it with a knife. Sodium can be cut easily with knife. Hence K and Na are soft metal cut with knife Activity 3.3 Page No. 38 Take pieces of iron, zinc, lead and copper try to strike it four or five times with a hammer. These metals are beaten into thin sheet on hammering. This property of metal is called malleability and metals are called malleable. Activity 3.4 Page

CBSE I NCERT 10th Numerical Problem solved Reflection and reflection of light

Q. 1. A concave mirror of focal length 20cm is placed 50 cm from a wall. How far from the wall an object be placed to form its real image on the wall?  Solution: V= -50 cm F= -20cm From mirror formula 1/u = 1/f – 1/v = -1/20+ 1/50 = - 3/100  U = - 33.3 cm Therefore, the distance of the object from the wall x =  50 – u X = 50 – 33.3 = 16.7 cm. Q.2. An object is placed at a distance of 40cm from a concave mirror of focal length 15cm. If the object is displaced through a distance of 20 cm towards the mirror, By how much distance is the image displaced? Answer: Here f = - 15 cm, u = - 40 cm Now 1/f = 1/u + 1/v Then 1/v = 1/f – 1/u Or V= uf/u-f =( - 40 x -15)/25 = -24 cm Then object is displaced towards the mirror let u1 be the distance object from the Mirror in its new position. Then u1 = -(40-20) = -20cm If the image is formed at a distance u1 from the mirror then v1 = u1f/u1-f = -20X-15/-20+15 = -60 cm. = - 20 x-15/-20+15 = -60 cm. Therefor

Electricity numerical for class 10 CBSE Trend Setter 50 Problems

1. The current passing through a room heater has been halved. What will happen to the heat produced by it? 2. An electric iron of resistance 20 ohm draws a current of 5 amperes. Calculate the heat produced in 30 seconds. 3. An electric heater of resistance 8 ohm takes a current of 15 A from the mains supply line. Calculate the rate at which heat is developed in the heater. 4. A resistance of 40 ohms and one of 60 ohms are arranged in series across 220 volt supply. Find the heat in joules produced by this combination in half a minute. 5. A resistance of 25 ohm is connected to a 12 V battery. Calculate the heat energy in joules generated per minute. 6. 100 joules of heat is produced per second in a 4 ohm resistor. What is the potential difference across the resistor? 7. An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at minimum heating’ it consumes a power of 360 W but at ‘maximum heating’ it takes a power of 840 W. Ca