Answers GCSS_Physical Science_ICRadioactivity

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Atoms of two different elements must have different

electrical charges.

numbers of neutrons.

atomic numbers.

energy levels.

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Calcium, magnesium, and strontium are near each other on the periodic table and have some characteristics in common, but they differ in chemical reactivity. Which lists these metals in order from most reactive to least reactive?

calcium, magnesium, strontium

magnesium, calcium, strontium

strontium, calcium, magnesium

strontium, magnesium, calcium

A sample is in the second half-life. What percent of the sample is stable at this point?

12.5%

25%

50%

75%

Which element is most likely to carry electric current easily?

tin (Sn)

sulfur (S)

antimony (Sb)

selenium (Se)

Which is the property of nonmetals to evaporate easily?

brittle

dense

liquid

volatile

Who was the first chemist to organize elements by atomic number?

Johann Wolfgang Döbereiner

Antoine Lavoisier

Henry Moseley

John Newlands

Sonya is studying a nonmetal element. She learns that the element is like other elements in its group because it can bond to form a salt or an acid. She also learns that the element is the most reactive element in its group. Which element is Sonya most likely studying?

sulfur (S)

neon (Ne)

fluorine (F)

iodine (I)

The atomic number of beryllium (Be) is 4, and the atomic number of barium (Ba) is 56. Which comparison is best supported by this information?

They are in the same group because they have similar atomic masses, but they are in different periods because they have different chemical properties.

They are in the same group because they have similar chemical properties, but they are in different periods because they have very different atomic numbers.

They are in the same group because their atomic numbers are each multiples of four, but they are in different periods because they have different chemical properties.

They are in the same group because they have similar atomic masses, but they are in different periods because they have very different atomic numbers.

Which describes radioactive decay of a substance?

More of the radioactivity is lost during the first half-life than in later half-lives.

More of the radioactivity is lost during the fourth half-life than in the first half-life.

Isotopes are the most stable during the first half-life.

Isotopes are the least stable during the later half-lives.

Three radioisotopes are being discussed in a chemistry class. Technetium-99m has a half-life of 6 hours. Rubidium-87 has a half-life of 50 billion years. Which describes who would most likely use each isotope?

A geologist would use technetium-99m because short-life indicates an older organism, and a doctor would use rubidium-87 because it allows for a more-accurate measurement of disease.

A doctor would use technetium-99m because a short half-life indicates a quick measurement, and a geologist would use rubidium-87 because a longer half-life means that there is a longer time to measure old rock.

A doctor would use technetium-99m because a short half-life indicates a quick measurement, and an archeologist would use rubidium-87 because anything containing carbon also contains rubidium.

A geologist would use technetium-99m because a short half-life indicates an older organism, and an archeologist would use rubidium-87 because anything containing carbon also contains rubidium.

Isra is analyzing the properties of several samples of elements to find out which sample is a metalloid. Which set of properties most likely belongs only to a metalloid?

forms basic compounds and is a solid

has a high luster and is very brittle

is a gas and has low electrical conductivity

is brittle and forms acidic compounds

These models show the electron structures of two different nonmetal elements.

Element 1 is more reactive because it has fewer electron shells and is toward the top of its group on the periodic table.

Element 1 is more reactive because it has more electrons in its valence shell and is farther to the right on the periodic table.

Element 2 is more reactive because it does not have a valence shell close to the nucleus, so it will attract electrons.

Element 2 is more reactive because it does not have a full valence shell, so it will attract electrons.

An atom of the element chromium has an atomic number of 24 and a mass number of 52. How many electrons are in an uncharged atom of chromium?

Which radioactive isotopes did the Curies discover?

polonium and radium

radium and carbon-14

carbon-14 and uranium

uranium and polonium

Which have different numbers of electrons?

different ions of an element

different isotopes of an element

the nucleus of an element

each of the atoms of an element

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