Question

choose the best answers.
3.011)____pink gold = yellow gold +
a. iron b. copper c. nickel
3.012)____which statement is true about the appearance of the mixture after mixing sugar with water?
a. it changes into a different color.
b. it looks the same as the water.
c. it does not change.
3.013)____what happens to the volume of 100 ml of vinegar when 50 ml of salt is dissolved in it?
a. the volume becomes smaller.
b. the volume stays about the same.
c. the volume becomes larger.
3.014)____if you mix 2 g of salt with 8 g of water, what is the total mass of the solution?
a. 2 g b. 6 g c. 8 g d. 10 g
3.015)____which chemists study of radiation has helped scientists to develop new treatments for cancer?
a. marie curie b. linus pauling c. rosalind franklin d. dmitri mendeleev
3.016) which three tools do chemists use?
hammer
balance
microscope
screwdriver
spectrometer

Explanation:

3.011)

Pink gold is an alloy made by combining yellow gold with copper. Iron is not typically used in making pink gold, and nickel is used in some other gold alloys but not for the characteristic pink color of pink - gold.

3.012)

When sugar is mixed with water, it dissolves. The sugar - water solution is clear and looks the same as pure water in terms of transparency (assuming no impurities). Sugar does not change the color of water (if it is pure water and pure sugar) and it does change the nature of the mixture (from just water to a sugar - water solution).

3.013)

When a solute (salt) is dissolved in a solvent (vinegar, which is mostly water), the volume of the solution does not increase proportionally to the volume of the solute. The salt particles fit into the spaces between the vinegar (water) molecules. So the volume stays about the same.

3.014)

According to the law of conservation of mass, the mass of the solution is the sum of the mass of the solute (salt) and the mass of the solvent (water). So \(m = 2g+8g=10g\).

3.015)

Marie Curie's work on radioactivity has had a profound impact on the development of cancer treatments (such as radiation therapy). Linus Pauling is known for work in chemistry (e.g., on chemical bonds), Rosalind Franklin for work on DNA structure, and Dmitri Mendeleev for the periodic table.

3.016)

• A balance is used to measure the mass of substances, which is crucial in chemistry for stoichiometry and determining amounts of reactants and products.
• A microscope can be used in some chemical analyses (e.g., to look at crystal structures or the morphology of precipitates in some cases).
• A spectrometer is used to analyze the interaction of light with matter, which can be used to identify substances, determine their concentration (e.g., UV - Vis spectroscopy for colored solutions), etc. A hammer and screwdriver are not typical chemical tools.

Answer:

3.011) B. copper
3.012) B. It looks the same as the water.
3.013) B. The volume stays about the same.
3.014) D. 10 g
3.015) A. Marie Curie
3.016) balance, microscope, spectrometer