Add 7xy+5yz – 3zx, 4xy + 9zx – 4y and -3xz +5xz – 2xy
Answers
Step-by-step explanation:
. A beggar wrapped himself with a few layers of newspaper on a cold winter night. This helped him to keep himself warm because
[A]. Friction between the layers of newspaper produces heat.
[B]. Air trapped between the layers of newspaper is a bad conductor of heat.
[C]. Newspaper is a conductor of heat.
[D]. Newspaper is at a higher temperature then the temperature of the surroundings.
2. Which of the following statement is incorrect?
[A]. Joule (J) is the SI unit of Temperature.
[B]. Air, water and wood are the poor conductor of heat.
[C]. Movement of molecule of liquid possible through convection.
[D]. None of the above.
3. An Iron ball at 40 Degree Celsius is dropped in a mug containing water at 40 Degree Celsius. The heat will
[A]. Flow from iron ball to water
[B]. Not flow from iron ball to water or from water to iron ball
[C]. Flow from water to iron ball
[D]. Increase the temperature of both
4. Convection may occur through
[A]. Solids, liquids
[B]. Liquids, gases
[C]. Solids, gases
[D]. Solids, liquids, gases
5. Once in a summer day, Pratima keeps an Iron chair in sunlight. After few hours, iron chair gets heated because
[A]. Heat is transferred by conduction
[B]. Heat is transferred by convection
[C]. Heat is transferred by radiation
[D]. Heat is transferred by all the process
Answer:
7xy+5yz-3zx+4xy+9zx-4y+(-3xz)+5xz-2xy
=7xy-2xy+4xy+5yz-3zx+9zx+4y-3xz+5xz
=9xy+5yz+3zx+4y+2xz
=9xy+5yz+5xz+4y......ans