name
blk.
study, work problems, answer questions. write the info on a separate paper or on this paper. this completed review is due the day you take the test. it has point value! some questions say omit, dont do those.
1 a bottle contains 10.0 ml of a liquid. the total mass of the bottle and the liquid together is 15.0g. the mass of the empty bottle is 5.0 g. what is the density of the liquid?
2 what is law of conservation of mass
3 which of the following substances is an element? (for a question like this you should look up information like, what is an element, how is it different from a mixture or compound? can i tell the difference if i were given choices; sodium chloride, iron, gasoline?)
4 an atom of an industrially important element contains 23 electrons and does not rust in the presence of air and moisture. identify the element.
5 which of the following elements is a metal?
6 according to ____ periodic table, the physical and chemical properties of elements are periodic functions of their atomic weights
7 what group are the alkaline earth metals? list two ____, ____, are they more reactive than group 1?
8 how many valence electrons are present in boron?
9 a formula unit of sodium bromide has one bromide ions corresponding to each sodium ion in the compound. what is the formula?
10 oxygen belongs to group 6a. how many covalent bonds are formed between two oxygen atoms? this could also use 1a and 7a groups in the questions (omit)
11 if the electronegativity of h is 2.20 and of f is 4.00, which type of bond is formed between hf?(2 nonmetals)
12 know examples of physical and chemical changes.
13 list the properties of the subatomic particles.(p, n, e-) charge, location, mass.
14 the emission of photons from the surface of a metal depends on the __?__ of incident light
15 which is more stable, an ion or an atom?

Question

Accepted Answer

### Question 1 Solution:
# Explanation:
## Step1: Find the mass of the liquid
The total mass of the bottle and liquid is $ 15.0\,\text{g} $, and the mass of the empty bottle is $ 5.0\,\text{g} $. So the mass of the liquid $ m $ is $ 15.0 - 5.0 = 10.0\,\text{g} $.
## Step2: Recall the density formula
Density $
ho $ is given by the formula $
ho=\frac{m}{V} $, where $ m $ is mass and $ V $ is volume.
## Step3: Calculate the density
The volume $ V $ of the liquid is $ 10.0\,\text{mL} $, and the mass $ m $ is $ 10.0\,\text{g} $. Substituting into the formula, we get $
ho=\frac{10.0\,\text{g}}{10.0\,\text{mL}} = 1.0\,\text{g/mL} $.
# Answer:
The density of the liquid is $ 1.0\,\text{g/mL} $.

### Question 2 Solution:
# Brief Explanations:
The law of conservation of mass states that in a closed system, mass is neither created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.
# Answer:
In a closed system, mass is neither created nor destroyed during a chemical reaction (total mass of reactants = total mass of products).

### Question 3 Solution:
# Brief Explanations:
An element is a pure substance consisting of only one type of atom. Sodium chloride ($ \text{NaCl} $) is a compound (made of $ \text{Na} $ and $ \text{Cl} $ ions), gasoline is a mixture, and iron ($ \text{Fe} $) is an element (consists of only $ \text{Fe} $ atoms).
# Answer:
Iron (Fe) is an element.

### Question 4 Solution:
# Brief Explanations:
In a neutral atom, the number of electrons equals the number of protons (atomic number). An atom with 23 electrons has an atomic number of 23, which is vanadium (V). Vanadium is resistant to rusting in air and moisture.
# Answer:
The element is vanadium (V).

### Question 5 Solution:
# Brief Explanations:
Metals are typically shiny, malleable, ductile, and good conductors. Common metals include sodium, iron, copper, etc. (depends on choices, e.g., if choices include sodium, it's a metal).
# Answer:
(Depends on options, e.g., if option is "Sodium", then Sodium is a metal)

### Question 6 Solution:
# Brief Explanations:
According to Mendeleev's periodic table, the physical and chemical properties of elements are periodic functions of their atomic weights.
# Answer:
Mendeleev's

### Question 7 Solution:
# Brief Explanations:
Alkaline earth metals are in Group 2 of the periodic table. Examples include magnesium (Mg) and calcium (Ca). They are less reactive than Group 1 (alkali metals) because they have 2 valence electrons (Group 1 has 1, easier to lose).
# Answer:
Group 2; Magnesium, Calcium; No (they are less reactive than Group 1).

### Question 8 Solution:
# Brief Explanations:
Boron has an atomic number of 5. Its electron configuration is $ 1s^2 2s^2 2p^1 $, so the number of valence electrons (electrons in the outermost shell, $ n = 2 $) is $ 2 + 1 = 3 $.
# Answer:
Boron has 3 valence electrons.

### Question 9 Solution:
# Brief Explanations:
Sodium (Na) has a charge of $ +1 $ (Na$^+$), and bromide (Br) has a charge of $ -1 $ (Br$^-$). To form a neutral compound, the formula is $ \text{NaBr} $ (one $ \text{Na}^+ $ and one $ \text{Br}^- $).
# Answer:
The formula of sodium bromide is $ \text{NaBr} $.

### Question 10 Solution:
# Brief Explanations:
Oxygen (Group 6A) has 6 valence electrons. To achieve an octet, each oxygen atom needs 2 more electrons. So two oxygen atoms form a double covalent bond ($ \text{O}=\text{O} $) to share 2 pairs of electrons (4 electrons total), satisfying the octet rule.
# Answer:
Two covalent bonds (a double bond) are formed between two oxygen atoms.

### Question 11 Solution:
# Brief Explanations:
The electronegativity difference ($ \Delta \chi $) between H (2.20) and F (4.00) is $ 4.00 - 2.20 = 1.80 $. A difference greater than 1.7 (approximate) indicates an ionic bond, but H and F are nonmetals, and the bond in HF is polar covalent (though some consider $ \Delta \chi \geq 1.7 $ ionic; however, HF is a polar covalent compound with a large dipole).
# Answer:
The bond in HF is a polar covalent bond (or ionic, depending on electronegativity difference criteria; typically considered polar covalent for HF).

### Question 12 Solution:
# Brief Explanations:
Physical changes: melting ice (state change, no new substance), dissolving sugar (no new substance). Chemical changes: burning wood (forms CO$_2$, ash), rusting iron (forms Fe$_2$O$_3$).
# Answer:
Physical changes: melting ice, dissolving sugar; Chemical changes: burning wood, rusting iron.

### Question 13 Solution:
# Brief Explanations:
- Proton (P): Charge $ +1 $, location (nucleus), mass $ \approx 1.67 \times 10^{-27}\,\text{kg} $ (or 1 amu).
- Neutron (N): Charge $ 0 $, location (nucleus), mass $ \approx 1.67 \times 10^{-27}\,\text{kg} $ (or 1 amu).
- Electron (e$^-$): Charge $ -1 $, location (electron cloud), mass $ \approx 9.11 \times 10^{-31}\,\text{kg} $ (or $ \frac{1}{1836} $ amu).
# Answer:
| Particle | Charge | Location | Mass |
|----------|--------|----------|------|
| Proton (P) | $ +1 $ | Nucleus | $ \approx 1.67 \times 10^{-27}\,\text{kg} $ |
| Neutron (N) | $ 0 $ | Nucleus | $ \approx 1.67 \times 10^{-27}\,\text{kg} $ |
| Electron (e$^-$) | $ -1 $ | Electron cloud | $ \approx 9.11 \times 10^{-31}\,\text{kg} $ |

### Question 14 Solution:
# Brief Explanations:
The emission of photons (photoelectric effect) from a metal surface depends on the frequency (or energy) of incident light. Below a threshold frequency, no electrons are emitted, regardless of intensity.
# Answer:
Frequency (or energy)

### Question 15 Solution:
# Brief Explanations:
Stability depends on the element. For reactive elements (e.g., alkali metals), ions (like Na$^+$) are more stable (noble gas configuration). For noble gases, atoms are stable. Generally, ions of reactive elements (with filled valence shells) are more stable than their atoms.
# Answer:
An ion is more stable than its atom for reactive elements (e.g., Na$^+$ is more stable than Na atom), but noble gas atoms are stable.

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Question 1 Solution:

Step1: Find the mass of the liquid

Step2: Recall the density formula

Step3: Calculate the density

Answer:

Question 2 Solution: