Choose the correct answer
1. SI unit of temperature is ______
a) celsius b) fahrenheit
c) kelvin d) ampere
2. The spherical mirror used as a rear view mirror in the vehicle is
a) concave mirror b) convex mirror
c) plane mirror d) None of the above
3. The range of audible frequency for the human ear is
a) 2 Hz to 2000 Hz b) 20 Hz to 2000 Hz
c) 20 Hz to 20000 Hz d) 200 Hz to 20000 Hz
4. The non-metal which conducts electric current is
a) carbon b) oxygen
c) aluminium d) sulphur
5. We brush our teeth with tooth paste because it is __________ in nature.
a) basic b) acidic
c) Both a and b d) None of these
6. The main component of natural gas is __________
a. methane b. ethane
c. propane d. butane
II Answer any 7 of the following
7. Expand CNG. List out its uses.
8. What is global warming?
9. Mention the various conditions required for a chemical reaction to occur.
10. What is ductility?
11. Distinguish between natural and artificial magnets?
Answers
Explanation:
1). C) kelvin
2). b) convex mirror
3). c) 20 Hz to 20000 Hz
4). a) carbon
5). c) Both a and b
6). a. methane
7). Answer: compressed natural gas,its uses are :Compressed natural gas (CNG) is a fuel that can be used in place of gasoline, diesel fuel and liquefied petroleum gas (LPG).
8). Global warming is the long-term heating of Earth's climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth's atmosphere.
9). Some of the major factors that play role in the chemical reaction are: surface area, catalyst, pressure, heat and light. The reaction in which heat energy is released during the chemical reaction is said to be an exothermic reaction. ... The catalyst that increases the rate of chemical reaction is positive catalyst.
10). Ductility is the ability of a material to be drawn or plastically deformed without fracture. It is therefore an indication of how 'soft' or malleable the material is. The ductility of steels varies depending on the types and levels of alloying elements present.
11). Natural magnets are the magnets that can be found in nature. For example - lodestone. Whereas artificial magnets are the magnets that are made by man. For example - electromagnet.