Answer:
1) rusting of metal is both chemical and physical change
2) black ice is an example of a physical change
Explanation:
when metal rusts, it is due to a reaction between the atoms in the metal and the atoms in the air(oxygen) or water(oxygen). When it rusts it also physically changes the look of the metal from silver to dirty brownish maroon.
Black ice is a change in state hence it cannot be a chemical change as the original substance NO LONGER EXISTS in a chemical reaction. It is a physical change however as the ice is changing into a different state of matter.
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Answer:
______is used in production of hard disk.
Explanation:
Answer:
V = 44.85 L
Explanation:
Given data:
Volume of H₂ = ?
Number of moles of H₂ = 2.0 mol
Given temperature = 273.15 K
Given pressure = 1 atm
Solution:
Formula:
PV = nRT
P = Pressure
V = volume
n = number of moles
R = general gas constant = 0.0821 atm.L/ mol.K
T = temperature in kelvin
By putting values,
1 atm × V = 2.0 mol × 0.0821 atm.L/ mol.K × 273.15 K
V = 44.85 atm.L / 1 atm
V = 44.85 L
In 1871, a Russian Chemist, Dimitri Mendeleev, gave a useful scheme for classification of elements. He presented the first regular periodic table in which elements of similar chemical properties were arranged in eight vertical columns called groups. The horizontal rows of table were called periods. He arranged elements in ascending order of their atomic masses and found that elements having similar chemical properties appeared at regular intervals. This observation was called Periodic Law.
