Chemistry Middle School
Answers
Answer 1
Answer:
B
Explanation:
physical changes do not change the chemical or molecular make up if a substance
Answer 2
Answer:
B. may involve a change in phase but does not involve a change in the molecular structure.
Explanation:
This is because a physical change is when a substance in changed but remains the same substance. For example if you freeze liquid water into ice it is still H2O.
Related Questions
WILL GIVE BRAINLIEST! What is the Celsius temperature scale based on?
vapor
the boiling point of air
the boiling and freezing points of water
the human body
Answers
The Celsius temperature scale is based on the boiling and freezing points of water.
The boiling point of water is 100 degrees Celsius.
The freezing point of water is 0 degrees Celsius.
Answer:
The Celsius temperature scale based on the boiling and freezing points of water
Explanation:
Temperature is defined as degree of coldness or hotness of a body or substance. And degree Celsius is one of the units in which it is measured.
A Celsius temperature scale s used to measure temperature in Celsius in which zero degree indicates freezing point of water and hundred degree Celsius indicates boiling point of water.
0° C = Temperature at which water freezes
100° C = Temperature at which water boils
Why is atom chargeless
Answers
From scientific conclusions that the metric sector will actually meet
Match the following questions with their answers based on the diagram below. 1.How many electrons are in the n = 2 shell of the oxygen atom before bonding?
2. What is the maximum number of electrons an oxygen atom can hold in its outer energy level?
3. How many total electrons are there in a water molecule?
4. How many electrons are being shared between the atoms in this molecule?
5.How many bonds exist in this molecule
two bonds
ten electrons
four electrons
eight electrons
six electrons
Answers
Answer:
I couldn't answer questions 4 and 5 since there was no image attached! I hope it helps!
Explanation:
1. There are six electrons in the n shell of the oxygen before bonding.
2. The maximum number of electrons that an oxygen atom can hold in its outer energy level is eight electrons.
3. There are ten electrons in a water molecule.
4. -
5. -
A biologist determines that a lizard's body temperature is 29 degrees C. Which of the following correctly describes the biologist's data? a) it is a qualitative observation b) it is a quantitative observation c) it is a prediction d) it is a classificatio
Answers
Answer:
B
Explanation:
It is a quantitative observation because quantitative data deals with values and numbers like height, weight, body temperature, etc.
The question also states that the biologist determines that the body temperature is 29⁰C, this is classified as an observation.
Hence, the answer is B, because the data is quantitative (as it contains numerical values), and the biologist observed this, most likely through a series of test.
Answer:
B
Explanation:
When an atom forms chemical bonds, its_becomes more stable
Answers
Answer:
The type of chemical bond maximizes the stability of the atoms that form it. An ionic bond, where one atom essentially donates an electron to another, forms when one atom becomes stable by losing its outer electrons and the other atoms become stable (usually by filling its valence shell) by gaining the electrons.
Explanation:
The mystery of periodic law was solved when __________ proposed his planetary atomic model of the atom, providing an understanding of the electronic structure of the elements and the organization of electrons into shells.
Answers
The mystery of periodic law was solved when _Bohr_ proposed his planetary atomic model of the atom, providing an understanding of the electronic structure of the elements and the organization of electrons into shells.
Answer:
The answer is BOHR
Explanation:
The fission of a nucleus is accompanied by the release of very little energy.
TRUE OR FALSE
Answers
The correct answer is false
Which of the following is a balanced chemical equation?Which of the following is a balanced chemical equation? A. AgNO3 + NaCl → 4AgCl + 2NaNO3
B. 2AgNO3 + 2NaCl → 3AgCl + 2NaNO3
C. AgNO3 + NaCl → AgCl + NaNO3
D. AgNO3 + 2NaCl → AgCl + 3NaNO3
Answers
The balanced chemical equation among the given chemical reactions is:
AgNO₃ + NaCl → AgCl +NaNO₃
What is the balanced chemical equation?
A balanced chemical equation exhibits reactants contributing to the reaction, formed products, and an arrow indicating the direction of the reaction.
In a balanced equation of a chemical reaction, the number of atoms of a specific element is equal on either side of the equation.
While balancing a chemical equation, the law of conservation of mass should be followed. The mass of anything can not be created or destroyed in a chemical reaction.
By obeying the law of conservation, the total mass of the reactants should be equal to the total mass of the products in a balanced chemical equation.
The equation in option C is the balanced chemical equation because the number of atoms Ag, N, Na, O, and Cl are equal on both sides of the chemical equation.
Learn more about the balanced chemical equation, here:
brainly.com/question/15052184
#SPJ2
Answer:
C.AgNO3 + NaCl → AgCl + NaNO3
Explanation:
Which of the following is a balanced chemical equation? A. AgNO3 + NaCl — 4A gC1 + 2NaNO3
B. 2AgNO3 + 2NaC1 — 3AgC1 + 2NaNO3
C. AgNO3 + NaCl - AgC1+ NaNO3
D. AgNO3 + 2Naci - AgCl + 3NaNO3
Answers
Answer:
AgNO3+NaCl+NaNo3 that's the answer
What is the density of 4 .8 grams of Oxygen gas at STP?
Answers
Answer:
- 1.4 g/liter
Explanation:
The density of a gas can be obtained using the gas ideal equation and the molar mass of the gas.
This is the decution of the final formula:
Now, you just need to substitute values:
- MM=32.0 g/mol
- p = 0.9869 atm
- T = 273.15 K
- R = 0.08206 atm-liter / k-mol
- Density = d = mass/V =
- d = 32.0 g/mol × 0.9869 atm / [0.08206 atm-liter/k-mol × 273.15K]
- d = 1.4 g/liter (using two significant figures)
As you see, I have not used the 4.8 grams datum. That is because the density of the gases may be calculated from the temperature, pressure and molar mass of the gas, using the ideal gas equation.
Since, you have the mass of gas, you might use this other procedure:
- Volume of 1 mol of gas at STP: about 22.4 liter/mol
- Mass of 1 mol of oxygen gas: 32.0 g/mol (the molar mass)
- number of moles in 4.8 g of oxygen = 4.8 g / 32.0 g/mol = 0.15 mol
- Volume of 0.15 mol of oxygen: 0.15 mol × 22.4 liter/mol = 3.36 liter
- Density = mass / volume = 4.8 g / 3.36 liter = 1.4 g/liter (same result)
What is the temperature of the substance when it is in its standard state?
Answers
The temperature of the substance at standard state is 25 °C.
Explanation
The standard state is the condition defined by the chemistry society to refer the temperature and pressure of any state of matter.
It is fixed for all the three states of matter. The standard state acts as reference for the change in temperature and pressure.
Generally, room temperature and pressure in a room without any external force is termed as standard conditions.
The parameters and properties for chemical reactions and elements are determined with respect to standard conditions for acting as a reference state.
So it is known that the room temperature or standard temperature is 25 °C and pressure is 1 bar.
Answer:
what substance????
.....,................,..... ........ ..........
If the solubility of copper chloride (CuCl2) is 151 g/dm3, how much copper chloride can be dissolved in 7.8 dm3 of water?
Answers
Answer:
- 1,200 g (rounding to two significant figures).
Explanation:
1) Data:
a) S = 151 g/dm³
b) mass = x
c) V = 7.8 dm³³
2) Formula for solubility, S:
- S = mass of solute / volume of solvent.
3) Solution:
- Substitute the data into the formula:
151 g/ dm³ = x / 7.8 dm³
- Solve for x:
x = 151 g/dm³ × 7.8 dm³ = 1,177.8 g.
Round to two significant figures (7.8 dm³ has two sig. fig.): 1,200 g
Answer:
1177.8
Explanation:
answer to educure
If the molar mass of the compound is 96.69 g/mol, what is the molecular formula of the compound?
NiF2
NiF
Ni2F4
Answers
Answer:
NiF2
Explanation:
The atomic weight (PA) is the average weight of the masses of the natural isotopes that make up a chemical element. The term refers to the relative atomic mass possessed by the atoms of each of the chemical elements.
One of the first units of the atomic weight, uma, was expressed in 1/16 (0.0625) of the weight of an oxygen atom.
This unit changed with the discovery of the existence of the natural isotopes of an element from 1912; therefore, the isotopes could no longer be ignored.
Currently, the standard unit of the atomic mass or dalton is 1/12 of the weight of the 12C isotope atom. This is more stable and abundant than 13C and 14C.
A unit of standardized atomic mass is the mass of a nucleon (a proton or a neutron) and equals 1 g / mol. This unification or standardization was performed with a C-12 atom to which 12 atomic mass units are assigned.
And so, the relative atomic weight or atomic mass can now be expressed in grams per one mole of atoms.
Molecular weight is the sum of the atomic masses of all atoms of a molecule of a specific compound. The atomic weight of an element is calculated by finding the weighted average mass of the mass of all isotopes thereof.
Calculation
Atomic mass:
- F: 18.9984 g/mol
- Ni: 58.6934 g/mol
Molecular formula: NiF2
Molecular mass: Ni (atomic mass) + F (atomic mass) * 2
58.6934 g/mol + (18.9984 g/mol) * 2
NiF2: 96.69 g/mol
Answer:
NiF2
Explanation: Ni: 58,71 g/mol
F: 19 g/mol
58,61+(19*2)= 96,71 g/mol
The density of a liquid is 0.739g/ml. What is the mass of 125ml of the sample
Answers
Answer:
92.375 g
Explanation:
Mass is found when you multiply density with volume
mass = density x volume
mass = 0.739g/ml x 125ml
mass = 92.375 g
If you need any clarification or more explanation pls do mention at the comment section.
Hope this helps and if it does pls mark as branliest answer thx
Which quantity is a graduated cylinder designed for measuring? OA. length
OB. mass
temperature
FROM. with that
YOU. volume
Answers
Answer:
E. Volume
Explanation:
A graduated cylinder is a piece of lab equipment used to measure volume. It is shaped like a narrow cylinder and is has markings on the side to help you measure the volume of a liquid.
NEED ANSWER FAST! The table compares the number of electrons in two unknown neutral atoms.
Comparison of Electrons
AtomNumber of Electrons
A 2
D 10
Use this information to determine the number of valence electrons in the atoms. Which of the following correctly compares the stability of the two atoms?
Both are unreactive.
Both are highly reactive.
A is unreactive and D is reactive.
A is reactive and D is unreactive.
Answers
Answer:
Both are unreactive.
Explanation:
Atom Number of Electrons
A 2
D 10
The two atoms A and D are very stable and unreactive.
Valence electrons the outermost shell electrons in a neutral atom.
The number of valence electrons in A is 2
The number of valence electrons in D is 8
The atoms are stable and unreactive because for A, its two electrons are in the k-shell in which the maximum number of electrons here is 2. It has a noble configuration which makes it stable.
For atom D, the outermost electrons are in the L-shell in which the maximum number of electrons is 8. This also makes it stable and unreactive.
Both atoms will be reluctant to lose or gain electrons.
Answer:
A). Both are unreactive
Explanation:
The table compares the masses of three unknown subatomic particles. Relative Mass of Particles
ParticleRelative Mass
P1
Q0.00054
R0.99
Which particle is most likely present in the nucleus of the atom?
Only particle P
Only particle Q
Both particles Q and R
Both particles P and R
Answers
Both particles P and R are present in the nucleus of the atom.
They are the proton and the neutron, but I can't remember right now which one of those has slightly more mass than the other one.
Particle Q is the electron. It takes about 1,850 electron masses to make one proton or neutron mass, and the electron is not in the nucleus.
Answer:
P and R
Explanation:
The table below compares the masses of three unknown subatomic particles:
Relative Mass of Particles
ParticleRelative Mass
P1
Q0.00054
R0.99
______________________________________________________
Both particles P and R are most likely present in the nucleus of the atom because the nucleus contains most of the mass in the atom.
How many electrons in an atom can have the quantum numbers n = 4, l = 0, ml = 0, ms = + 1/2 ? 1
2
3
6
Answers
Only one electron in an atom can have the quantum numbers; n = 4, l = 0, ml = 0, ms = + 1/2.
According to Pauli exclusion theory, no two electrons in an atom can have the same value for all the four quantum numbers. Even if two electrons are present in the same orbital, the values of their spin quantum number must differ in obedience to Pauli exclusion theory.
Therefore, only one electron in an atom can have the quantum numbers; n = 4, l = 0, ml = 0, ms = + 1/2.
Learn more: brainly.com/question/9847214
Answer:
The answer is 1.
Explanation:
Four quantum numbers are used to describe an electron:
n is the Principal quantum number which deals with its energy state,
l is the Azimuthal quantum number which describes its angular momentum,
m or ml is the Magnetic quantum number which relates to magnetic,
s or ms is the Spin quantum number which covers spin.
Each electron is unique in its set of quantum numbers. So there can only be one.
What is the overall electric charge for individual atoms on the periodic table of elements?
Answers
Explanation:
All the atoms present in periodic table are neutral in nature and it is known that a neutral atom means that it contains no charge.
For example, sodium is present as Na in the periodic table. And, it does not contain any charge.
When a neutral atom loses or gains an electron then it acquires a charge.
For example, atomic number of calcium is 20 and its electronic distribution is 2, 8, 8, 2. Hence, in order to acquire stability when it loses 2 valence electrons then neutral atom of Ca changes into .
Hence, it means that by loosing 2 valence electrons calcium has an electric charge of +2.
Answer:
Neutral
Explanation:
Atoms on the periodic table all have neutral electric charges. This is because they have an equal number of protons, which are positivly charged, and electrons, which are negatively charged.
What dose the word scientific method means
Answers
Answer:
Scientific Method - steps to use when doing an experiment.
1. Make a question
2. Do some Research
3. Hypothesis - make a guess
4. Test and Collect Data
5. A conclusion