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Answer:
a. True
Explanation:
From Thomson's Plum Postulate on Pudding model of an atom, he posits that particle includes electrons that are encircled by a circle of positive charge to adjust the negative charges of electrons, which is fundamentally the same as way like negatively charged "plums" is getting encased by positively charged pudding.
Hence, the above statement is true.
The density of Ca will be between that of Mg and Sr
Explanation:
Ca, Mg and Sr are group II elements. They are called alkali earth metals. The correct order of the elements in this group are: Be, Mg, Ca, Sr, Ba and Ra.
Density is an intensive property of matter which describes the amount of matter(mass) per volume of a substance.
- Density varies proportionally with mass. The higher the mass, the higher its density.
- On the periodic table, atomic mass which the number of protons and neutrons in the nucleus of an atom increases down the group.
- This implies a progradation in the value of density down the group. Therefore one expects that the value of density of Ca will fall between that of Mg and Sr. It cannot be more than 2.6g/cm³ nor less than 1.74g/cm³.
Learn more:
density brainly.com/question/2658982
mass number brainly.com/question/2597088
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Compressions are regions of high pressure due to particles being close together
rarefactions are regions of low pressure due to particles being spread further apart
Longitudinal waves are often demonstrated by pushing and pulling a stretched slinky spring