The water is at lower temperature than the ice
Energy is absorbed when the ice changes to water
Energy is released when the ice changes to water
The water molecules vibrate about a fixed point
Correct answer is B
Heat energy near the ice gets absorbed into the ice. The energy breaks the bonds of the ice, causing it to melt into liquid water. On other words, when ice melts, the energy gets absorbed into the water.
The following factors would contribute to environmental pollution except
production of ammonia
manufacture of cement
photosynthesis
combustion
Correct answer is C
Photosynthesis is the process of food-making in plants, it doesn't have any by-products that pose a threat to the environment. Infact, the plants use our waste product of respiration (Carbon dioxide) and uses it for the photosynthetic process and gives off oxygen as by-product.
The most suitable substance for putting out petrol fire is
water
carbon(IV) oxide
fire blanket
sand
Correct answer is B
In order to extinguish a petrol fire, you have to cut off the oxygen. This can be done by using carbon dioxide gas to dilute the oxygen available and stop the burning.
Stainless steel is an alloy comprising of
Fe and C
Fe and Ni
Fe, C and Ni
Fe, C and Al
Correct answer is C
Stainless steel comprises iron (Fe), chromium (Cr), manganese (Mn), silicon (Si), carbon (C) and, in many cases, significant amounts of nickel (Ni) and molybdenum (Mo).
The valence electrons of \(_{12}Mg\) are in the
3s orbital
2p\(_{x}\)
2s orbital
1s orbital
Correct answer is A
\(_{12}Mg = 2, 8, 2\)
\(= 1s^{2} 2s^{2} 2p^{6} 3s^{2}\)
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