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Ask QuestionPosted by Savita Vishnoi 4 years, 8 months ago
- 2 answers
Yogita Ingle 4 years, 8 months ago
Metals react with acids to produce hydrogen gas. If a matchstick is brought near the mouth of the tube containing the product of the reaction then we hear a pop sound. It is this hydrogen gas that burns with a pop sound.
- For instance, Magnesium reacts with dilute hydrochloric acid to form magnesium chloride and hydrogen.
- Copper does not react with hydrochloric acid but reacts with sulphuric acid.
Posted by Roshan Rana Magar 4 years, 8 months ago
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Yash Malhotra 4 years, 8 months ago
Posted by Asharani M 4 years, 8 months ago
- 5 answers
Gaurav Seth 4 years, 8 months ago
Decibel
Sound is another form of energy that travels in the form of waves either through a liquid, air, or even solid substances. Since this energy can be measured, the most common SI unit of sound that is used is Decibel which is abbreviated as dB.
Posted by Bhumika Choudhary 4 years, 8 months ago
- 1 answers
Gaurav Seth 4 years, 8 months ago
The following are the benefits of car pooling:
1. It is Cost effective.
2. It results in reduction of pollution
3. It leads to reduction traffic on roads.
4. It helps in saving of fossil fuels.
Posted by Banarasiya Don???? 4 years, 8 months ago
- 1 answers
Gaurav Seth 4 years, 8 months ago
When there is more than one force acting upon the same body. The different forces is altogether replaced by a single force. This force is called resultant force.
The formula of resultant force is F∨R = F∨1 + F∨2 + F∨3
If the force F∨2 is perpendicular to the force F∨1 then the formula is
F∨R = F∨1 + F∨3 - F∨2
EXAMPLE --
If three forces 60N , 45N and 30N are acting on a body simultaneously. 30N is opposite to the direction of other two. Calculate the resultant force.
SOLUTION --
As per the formula we will place the quantities.
(60N + 45N) - 30N
105N - 30N
= 75N
Hence, the resultant force for the question asked is 75N.
Posted by Ayush Sharma 4 years, 8 months ago
- 2 answers
Yash Malhotra 4 years, 8 months ago
Posted by Bani Singh Bani Singh 4 years, 8 months ago
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Shreya Jha 4 years, 8 months ago
Aryaman Pandey 4 years, 8 months ago
Posted by Vivek Kumar 4 years, 8 months ago
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Ayush Sharma 4 years, 8 months ago
Posted by Banarasiya Don???? 4 years, 8 months ago
- 4 answers
Posted by Nikhil Kumar 4 years, 8 months ago
- 5 answers
Bani Singh Bani Singh 4 years, 8 months ago
Gaurav Seth 4 years, 8 months ago
Non-contact Forces : The force experienced by the bodies even without being physically touched, are called non-contact forces. e.g. Gravitational force, Magnetic force.
Posted by Nikhil Kumar 4 years, 8 months ago
- 4 answers
Shreya Jha 4 years, 8 months ago
Bani Singh Bani Singh 4 years, 8 months ago
Gaurav Seth 4 years, 8 months ago
Contact Forces : The forces which are applied on bodies by making a physical contact with them, are called contact forces. e.g. the force of friction (frictional force), normal reqction force
Posted by Bhumika Choudhary 4 years, 8 months ago
- 2 answers
Gaurav Seth 4 years, 8 months ago
(a) Saloni should add some water in the test tube in which gas was collected. Shake the test tube and then bring a litmus paper near the test tube.The solution will turn litmus paper red. This shows that the gas is acidic.
(b)Charcoal contains carbon which on burning forms carbon dioxide gas.
C+O_2→CO_2C+O2→CO2
The gas evolved is collected in a test tube and water is added to it.
CO_2+H_2O→H_2CO_3CO2+H2O→H2CO3
Posted by Vipul Atri 4 years, 8 months ago
- 4 answers
Shreya Jha 4 years, 8 months ago
Shreya Jha 4 years, 8 months ago
Banarasiya Don???? 4 years, 8 months ago
Gaurav Seth 4 years, 8 months ago
In order to provide food for a large population – regular production, proper management and distribution of food is necessary.
Crop: When plants of the same kind are grown and cultivated at one place on a large scale, it is called a crop.
- In India, crops can be broadly categorised into two types based on seasons – Rabi and Kharif crops.
- Sowing of seeds at appropriate depths and distances gives good yield. Good variety of seeds are sown after selection of healthy seeds. Sowing is done by seed drills.
- Soil needs replenishment and enrichment through the use of organic manure and fertilisers. Use of chemical fertilisers has increased tremendously with the introduction of new crop varieties.
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<a data-ved="2ahUKEwjp8o747-rtAhXWTX0KHZmVBUYQFjAAegQIBRAC" href="https://mycbseguide.com/blog/cbse-class-8-science-revision-notes/" ping="/url?sa=t&source=web&rct=j&url=https://mycbseguide.com/blog/cbse-class-8-science-revision-notes/&ved=2ahUKEwjp8o747-rtAhXWTX0KHZmVBUYQFjAAegQIBRAC" rel="noopener" target="_blank">CBSE Class 8 Science Revision Notes | myCBSEguide ...</a>
Posted by Banarasiya Don???? 2 years, 6 months ago
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Gargi Bhiwapurkar 2 years, 6 months ago
Posted by Banarasiya Don???? 4 years, 8 months ago
- 1 answers
Gaurav Seth 4 years, 8 months ago
Incident ray : Incident ray is define as that ray of light which falls on the mirror surface. Here AO is the incident ray.
⇒Reflected ray : The ray of light which is sent back by the mirror is known as reflected ray. Here OB is the reflected ray.
⇒Point of incidence : The point at which incident ray falls on the mirror is called point of incident . Here o is the point of incidence.
⇒Normal : The normal is the line at right angle to the mirror surface at the point of incidence.
⇒Angle of incidence : This is the angle made by the incident ray with the normal at the point of incidence.
⇒Angle of reflection : This is the angle made by the reflected ray with the normal at the point of incident.
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Posted by Ashwin Jadhav 4 years, 8 months ago
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Posted by Ashwin Jadhav 4 years, 8 months ago
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Posted by Ayush Pawar 4 years, 8 months ago
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Yogita Ingle 4 years, 8 months ago
The endocrine glands release hormones into bloodstream to reach a particular body part called target site. The target site responds to the hormone. the particular site where the hormones reach through the bloodstream is called the target site.
Posted by Ayush Pawar 4 years, 8 months ago
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Shruti ? 4 years, 8 months ago
Posted by Bani Singh Bani Singh 4 years, 8 months ago
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Shruti ? 4 years, 8 months ago
Posted by Ramanpreet Kaur 4 years, 8 months ago
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Gaurav Seth 4 years, 8 months ago
i-low, ii-spontaneous, iii-Kerosene
The minimum temperature at which a substance catches fire is called ignition temperature. The ignition temperature of sodium is very low. Hence, it catches fire easily at room temperature. It reacts vigorously with oxygen at room temperature. To prevent its spontaneous combustion, it is stored under kerosene.
Posted by Bani Singh Bani Singh 4 years, 8 months ago
- 2 answers
Gaurav Seth 4 years, 8 months ago
The SI unit of pressure is Pascal (represented as Pa) which is equal to one newton per square metre (N/m-2 or kg m-1s-2). Interestingly, this name was given in 1971. Before that pressure in SI was measured in newtons per square metre.
Pascal Formula:
Posted by Sai Varsha 4 years, 8 months ago
- 3 answers
Aaruhi Shukla 4 years, 8 months ago
Gaurav Seth 4 years, 8 months ago
The Acts of Union, passed by the English and Scottish Parliaments in 1707, led to the creation of the United Kingdom of Great Britain on 1 May of that year. ... The idea of a union between England and Scotland was aired in February and March 1689 during the deliberations of the Convention Parliament in Edinburgh.
Yogita Ingle 4 years, 8 months ago
Synthetic fibres are man-made fibres, most of them are prepared from raw material petroleum called petrochemicals. All fabrics are obtained from fibres, while fibres are obtained from artificial or man-made sources. They consist of a small unit or a polymer which is made from many repeating units known as monomers. They include nylon, acrylics, polyurethane, and polypropylene. Millions of tons of these fibres are produced all over the world each year.
Posted by Mahesh Yadav Kotla 4 years, 8 months ago
- 1 answers
Gaurav Seth 4 years, 8 months ago
Some fibres are called synthetic because they are not made from natural fibres. Instead, they are made by chemical processing of petrochemicals. The synthetic fibres are made up of very large units called polymers. Some of the synthetic fibres are - nylon, rayon, acrylon.
Posted by Simran Singh 4 years, 8 months ago
- 2 answers
Niraj Chaudhary 4 years, 8 months ago
Yogita Ingle 4 years, 8 months ago
at the time of puberty, and usually is around two years earlier in females than man.
The secondary sexual characteristics in males are :
Hair growth on the face in the form of beard and moustache
The growth of his testicles
Heavier musculature
Adam's apple development
Larynx becomes larger results in a deeper voice
Some of the changes appear in females are:
Development of breast
Lighter musculature
Shrill and a higher pitch voice
Broadening of hips due to fat deposition
Posted by Ankit Chhawadi Rashmi Chhawdi 4 years, 8 months ago
- 1 answers
Yogita Ingle 4 years, 8 months ago
Two examples of push force are as follows:
- A heavy box at rest is pushed to move it from one room to another. This changes the state of motion of the box.
- A player pushes a football using his foot. This changes the state of motion of the ball.
Two examples of pull force are as follows:
- Rope is pulled to draw water from a well. This changes the state of motion of the water bucket.
- A drawer is pulled to open it. This changes the state of motion of the drawer.
Posted by Kishore K.V 4 years, 8 months ago
- 4 answers
Gaurav Seth 4 years, 8 months ago
The moon never actually falls on the surface of the earth.
Now, to understand this, we first need to understand the nature of the force between the moon and earth and also the movement of the moon under this force.
So, the gravitational force is the force that acts between the earth and the moon, and the moon moves in the circular orbital due to the centripetal force generated by the gravitational force.
Similarly, earth and sun also experience this gravitational force between themselves.
So, yes the moon does fall towards the earth, but the earth also moves in its orbit and covers more distance away from the moon relative to the distance covered by the moon.
Hence, the moon never falls on the surface of the earth
Posted by Tania Sharma 4 years, 8 months ago
- 3 answers
Gaurav Seth 4 years, 8 months ago
A n s w e r:
A rough surface causes more friction because the irregularities on the rough surface are more when compared to the smooth surface. These irregularities helps in increasing the friction.
Hardik Garg 4 years, 8 months ago
Posted by Khushi Goyal 4 years, 8 months ago
- 1 answers
Gaurav Seth 4 years, 8 months ago
Ans:
static, sliding, rolling
Friction comes into play when irregularities present in the surfaces of two objects in contact get interlocked with each other. Static friction comes into play when we try to move an object which is at rest. Sliding friction comes into play when an object slides over the surface of another object. In sliding friction, the time given for interlocking is very small. Hence, interlocking is not strong. Therefore, less force is required to overcome this interlocking. Because of this reason, sliding friction is less than static friction. Similarly, the area of contact in case of rolling friction is smallest as compared to static or sliding friction. This area of contact changes gradually because of rolling. Hence, rolling friction is lesser than both static and sliding friction. Thus, the correct sequence is—static, sliding, rolling
Posted by Khushi Goyal 4 years, 8 months ago
- 1 answers
Gaurav Seth 4 years, 8 months ago
static, sliding, rolling
Friction comes into play when irregularities present in the surfaces of two objects in contact get interlocked with each other. Static friction comes into play when we try to move an object which is at rest. Sliding friction comes into play when an object slides over the surface of another object. In sliding friction, the time given for interlocking is very small. Hence, interlocking is not strong. Therefore, less force is required to overcome this interlocking. Because of this reason, sliding friction is less than static friction. Similarly, the area of contact in case of rolling friction is smallest as compared to static or sliding friction. This area of contact changes gradually because of rolling. Hence, rolling friction is lesser than both static and sliding friction. Thus, the correct sequence is—static, sliding, rolling
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Yash Malhotra 4 years, 8 months ago
1Thank You