Question

i've got 5 wrong ...
all of my answers
but who can help me find out which 5 i've got wrong because they never told me ..





1.c'
2b
3d
4a
5a
6b
7c
8d

9a
10d
11a
12a
13d
14b
15
16a
17d
18c
19c
20a
21c
22b
23d
24a
25a
26c
27c
28b
29b
30a
31c
32a
33a
34c
35b
36a
37a
38a
39a
40a
41d
42c

Answer 1

1.
How are science and technology related? (1 point)
• Technology is a branch of natural science.
• Science is a branch of technology.
• Advances in science may lead to advances in technology and vice versa.
• Science and technology are not related.
2.
Why are scientific models important? (1 point)
• They prove scientific theories.
• They help visualize things that are very complex, very large, or very small.
• They make it harder to understand things.
• They never change.
3.
Timers at a swim meet used four different clocks to time an event. Which recorded time is the most precise? (1 point)
• 55 s
• 55.2 s
• 55.25 s
• 55.254 s
4.
If the relationship between the manipulated variable and the responding variable is a direct proportion, what will a line graph of this relationship look like? (1 point)
• a straight line
• a curved line
• a jagged line
• none of the above
5.
Which of the following is NOT a pure substance? (1 point)
• milk
• oxygen
• water
• carbon dioxide
6.
Water is a compound because it (1 point)
• can be broken down into simpler substances.
• always has two hydrogen atoms for each oxygen atom.
• is made of water atoms joined together.
• both a and b
7.
Which of the following is a heterogeneous mixture? (1 point)
• water in a swimming pool
• sugar water
• a jar of mixed nuts
• stainless steel
8.
Filtration can be used to separate mixtures based on (1 point)
• their boiling points.
• their densities.
• their melting points.
• the size of their particles.
9.
Which of the following is a physical change? (1 point)
• sawing a piece of wood in half
• burning a piece of wood
• rust forming on an iron fence
• a copper roof changing color from red to green
10.
Which of the following is a clue that a chemical change has occured? (1 point)
• Iron changes color when heated.
• Gas bubbles form in boiling water.
• Balls of wax form when melted wax is poured into ice water.
• A gas forms when vinegar and baking soda are mixed.
11.
Forces of attraction limit the motion of particles most in (1 point)
• a solid.
• a liquid.
• a gas.
• both b and c
12.
Which of the following will cause a decrease in gas pressure in a closed container? (1 point)
• lowering the temperature
• reducing the volume
• adding more gas
• both a and b
13.
If a solid piece of naphthalene is heated and remains at 80°C until it is completely melted, you know that 80ºC is the (1 point)
• freezing point of naphthalene.
• melting point of naphthalene.
• boiling point of naphthalene.
• both a and b
14.
During which phase change does the arrangement of water molecules become more orderly? (1 point)
• melting
• freezing
• boiling
• condensing
15.
The phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first is (1 point)
• sublimation.
• deposition.
• vaporization.
• melting.
16.
Which phase change is an endothermic change? (1 point)
• condensation
• vaporization
• deposition
• freezing
17.
How was Bohr’s atomic model similar to Rutherford’s model? (1 point)
• It assigned energy levels to electrons.
• It described electron position in terms of the electron cloud model.
• It described how electrons gain or lose energy.
• It described a nucleus surrounded by a large volume of space.
18.
What is the difference between an atom in the ground state and an atom in an excited state? (1 point)
• The atom in the ground state has less energy and is less stable than the atom in an excited state.
• The atom in an excited state has one fewer electron than the atom in the ground state.
• The atom in an excited state has more energy and is less stable than the atom in the ground state.
• The atom in an excited state has one more electron than the atom in the ground state.
19.
The usefulness of Mendeleev’s periodic table was confirmed by (1 point)
• the discovery of subatomic particles.
• its immediate acceptance by other scientists.
• the discovery of elements with predicted properties.
• the discovery of the nucleus.
20.
The atomic mass of an element is (1 point)
• the sum of the protons and neutrons in one atom of the element.
• twice the number of protons in one atom of the element.
• a ratio based on the mass of a carbon-12 atom.
• a weighted average of the masses of an element’s isotopes.
21.
Which general statement does NOT apply to metals? (1 point)
• Most metals are ductile.
• Most metals are malleable.
• Most metals are brittle.
• Most metals are good conductors of electric current.
22.
Among the alkali metals, the tendency to react with other substances (1 point)
• does not vary among the members of the group.
• increases from top to bottom within the group.
• varies in an unpredictable way within the group.
• decreases from top to bottom within the group.
23.
Study the electron dot diagrams for lithium, carbon, fluorine, and neon in Figure 6-1. Choose the statement that correctly identifies the most stable of the elements.

(1 point)
• Lithium is the most stable element because it has to lose only one electron to achieve a stable configuration.
• Carbon is the most stable element because it can form four bonds.
• Fluorine is the most stable element because it has to gain only one electron to achieve a stable configuration.
• Neon is the most stable element because its highest occupied energy level is filled.
24.
The formation of an ionic bond involves the (1 point)
• transfer of electrons.
• transfer of neutrons.
• transfer of protons.
• sharing of electrons.
25.
In a polar covalent bond, (1 point)
• electrons are shared equally between atoms.
• a cation is bonded to an anion.
• electrons are transferred between atoms.
• electrons are not shared equally between atoms.
26.
Beryllium, Be, and chlorine, Cl, form a binary ionic compound with a one-to-two ratio of beryllium ions to chloride ions. The formula for the compound is (1 point)
• Be2Cl.
• BeCl.
• BeCl2.
• Be2Cl2.
27.
When magnesium carbonate, MgCO2, reacts with nitric acid, HNO3, magnesium nitrate and carbonic acid form. Carbonic acid then breaks down into water and carbon dioxide. Which two types of reactions take place in this process? (1 point)
• synthesis and decomposition
• single-replacement and combustion
• double-replacement and decomposition
• double-replacement and combustion
28.
In terms of energy, how would you classify the following chemical reaction?

2Cu + O2 2CuO + 315 kJ (1 point)
• endothermic
• exothermic
• both endothermic and exothermic
• neither endothermic nor exothermic
29.
A log is burning in a fireplace. If the amount of oxygen reaching the log is decreased, which of the following statements is true? (1 point)
• The reaction rate increases.
• The reaction rate decreases.
• The reaction rate remains the same.
• The reaction rate depends only on the temperature.
30.
A student dissolved equal amounts of salt in equal amounts of warm water, room-temperature water, and ice water. Which of the following is true? (1 point)
• The salt dissolved most quickly in the warm water.
• The salt dissolved most quickly in the room-temperature water.
• The salt dissolved most quickly in the ice water.
• none of the above
31.
A solution that contains more solute than it would normally hold at that temperature is said to be (1 point)
• saturated.
• unsaturated.
• supersaturated.
• concentrated.
32.
Which of the following is NOT a property of an acid? (1 point)
• tastes sour
• usually reacts with a metal
• changes the color of an indicator
• feels slippery
33.
A base is defined as a compound that produces (1 point)
• hydroxide ions in solution.
• hydrogen ions in solution.
• hydronium ions in solution.
• sodium ions in solution.
34.
A small amount of acid is added to a buffer solution. The pH of the solution will (1 point)
• increase.
• decrease.
• stay about the same.
• become neutral.
35.
Uranium-238 undergoes alpha decay. Therefore, uranium-238 will (1 point)
• remain stable.
• change into a different element altogether.
• emit neutral particles and no energy.
• none of the above
36.
What type of radiation is emitted when polonium-212 forms lead-208? (1 point)
• an alpha particle
• a beta particle
• gamma radiation
• all of the above
37.
Transmutation involves (1 point)
• nuclear change.
• chemical change.
• both a nuclear change and a chemical change.
• neither a nuclear nor a chemical change.
38.
During nuclear fission, great amounts of energy are produced from (1 point)
• very small amounts of mass.
• tremendous amounts of mass.
• a series of chemical reactions.
• particle accelerators.
39.
Which of the following conversion factors would you use to change 18 kilometers to meters? (1 point)
• 1000 m/1 km
• 1 km/1000 m
• 100 m/1 km
• 1 km/100 m
40.
According to John Dalton’s observations, when elements combine in a compound, (1 point)
• the ratio of their masses is always the same.
• each element contributes an equal number of atoms.
• their volumes are always equal.
• their masses are always equal.
41.
Which of the following provides the best analogy for an electron in an atomic orbital? (1 point)
• a bee moving from flower to flower in a garden
• a bird resting on a tree branch
• an ant crawling on the surface of a leaf
• a bee trying to escape from a closed jar
42.
The tendency of an element to react is closely related to (1 point)
• its atomic mass.
• attractions between its atoms.
• the number of valence electrons in atoms of the element.
• the ratio of protons to neutrons in atoms of the element.
Short Answer

Note: Your teacher will grade your responses to questions 43–50 to ensure that your receive proper credit for your answers.
43.
If a gas has a volume of 1 L at a pressure of 270 kPa, what volume will it have when the pressure is increased to 540 kPa? Assume the temperature and number of particles are constant. (1 point)

44.
How many grams of O2 are in 5.0 moles of the oxygen gas? (1 point)

45.
What are the products of a neutralization reaction? (2 points)

46.
Sodium reacts with chlorine gas to form sodium chloride. Write a balanced chemical equation for the reaction, and find the mass of chlorine gas that will react with 96.6 g of sodium. (3 points)

47.
After 15 minutes, 30 g of a sample of polonium-218 remain unchanged. If the original sample had a mass of 960 g, what is the half-life of polonium-218? (1 point)

Essay
48.
Explain the difference between a physical equilibrium and a chemical equilibrium. (3 points)

49.
Suppose you want to separate the leaves, acorns, and twigs from a pile of soil. Filtration and distillation are two processes of separating mixtures. Explain which process you would use and why. (3 points)

50.
What is the charge on the subatomic particles represented in Figure 4-3? Assuming all the particles in the nucleus are visible, what are the atomic and mass numbers of the atom shown?

(4 points)

Answer 2

15* is c

Answer 3

What is 50

Answer 4

@Typrice did you get it? can you please help me