19. Which atom will have the smallest size (atomic radius) b. Te c. S d. Se 20.

Question

19. Which atom will have the smallest size (atomic radius) b. Te c. S d. Se 20. Which atom will have the greatest electronegativity a. F b. O d. Cl 21. Which of the following facts about the element phosphorus is true a. its discoverer, Hennig Brand, isolated it from sea water b. it has been known since antiquity (the BC era) c. it ignites spontaneously on exposure to air d. it is non-toxic 22. Rayleigh and Ramsey discovered a. the law of triads b. many of the group 18 gases c. the first radioactive elements d. the law of octaves 23. An examination of the nature of elements in the periodic table reveals a. most elements are solids at room temperature b. most elements are not naturally radioactive c. most elements are metals d. all the above are true 24. Which of the following elements would behave chemically similar to Ca d. Mg a. Na b. S c. C 25. Which best describes how metals and non-metals differ a. metals generally have low melting points b. metals prefer to gain electrons c. metals do not exist as diatomic molecules d. non-metals prefer to lose electrons 26. Which of the following statements is false a. all UV radiation is absorbed by the ozone layer b. UV radiation can damage cellular DNA c. Skin sensitivity is a factor in sunburning d. Using a sunscreen with an SPF factor of 35 offers more protection than one with a SPF of 15 27. Going down a group in the periodic table, the size of the atoms will a. vary irregularly b. decrease c. increase d. remain constant

Explanation / Answer

19.

In groups from top to bottom, the atomic radius increases

So Oxygen (O) atom will have smallest size

20.

Fluorine is most electronegative, because in periods, the electronegativity increases

21.

Elemental phosphorous was discovered by Hennig Brand, isolated from sea water

22.

Rayleigh and Ramsay discovered many of the group 18 gases (noble gases)

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