Answer:
if you want to find average speed so u need to use this formula
Average speed = 
A chemical reaction (signs)
- rusting
- change in base of chemical
- for example lets say u mix two chemicals, and then it becomes a different new chemical (it changed from the inside)
a physical
- a physical reaction is outer looks not inside.
- it changes on the outside, like changing a color
While the material retains its chemical makeup, the physical property may be examined. The given statement is true.
The matter can undergo variations in physical or chemical properties. The physical changes of a matter occur when the matter undergoes changes in its physical properties like changes in the state of matter, weight, color, etc.
But the chemical composition of matter will remain constant if it undergoes a physical change. Whereas in chemical change, the matter undergoes a change in the composition of the substance but there will be no change in the physical properties.
Hence, The assertion is correct in that physical properties can be seen while the substance's chemical makeup stays constant.
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Answer: The volume of 0.640 grams of 
gas at Standard Temperature and Pressure (STP) is 0.449 L.
Explanation:
Given: Mass of gas = 0.640 g
Pressure = 1.0 atm
Temperature = 273 K
As number of moles is the mass of substance divided by its molar mass.
So, moles of (molar mass = 32.0 g/mol) is as follows.
Now, ideal gas equation is used to calculate the volume as follows.
PV = nRT
where,
P = pressure
V = volume
n = no. of moles
R = gas constant = 0.0821 L atm/mol K
T = temperature
Substitute the values into above formula as follows.
Thus, we can conclude that the volume of 0.640 grams of gas at Standard Temperature and Pressure (STP) is 0.449 L.
The correct answer is higher melting point, bound by metal metal bonds.
While alkali metals only have one valence electron, alkaline earth metals have two. Metal to metal connections hold the metals together. Alkaline earth metals have a stronger metallic connection and a higher melting point because they have two valence electrons.
the characteristics that Group 2 metals excel in over Group 1 metals.
- Initial Ionization Potential
- Group 2 items are more difficult than group 1 elements.
- Strong propensity to produce bivalent compounds
As a result, group 2 metals have stronger metallic bonding, which leads to increased cohesive energy and compact atom packing. This explains why group 2 metals are harder and have higher melting and boiling temperatures than group 1 metals.
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