Answer:
The atomic numbers of four elements A, B, C, and D are 6,8,10, and 12 respectively. The two elements which can react to form ionic bonds (or ionic compounds) are B (8= 2,6) and D (12 =2,8,2). So D donates its two electrons to B to fulfill their octet.
Explanation:
How does the weather caused by a warm front compare to the weather caused by a cold front?
A: A warm front brings fog, but a cold front brings clouds that form from dry air.
B: A warm front brings rapid changes in weather, but a cold front brings slow changes in weather.
C: A warm front brings widespread cloud cover, but a cold front brings intense sun coverage.
D: A warm front brings rain in humid air on occasion, but a cold front brings thunderstorms in summer.
Answer:
The weather caused by a warm from and a cold front compare by:
D. A warm front brings rain in humid air on occasion, but a cold front brings thunderstorms in summer.
A warm front is a phenomenon in which a warm air mass replaces a cold air mass, creating fog and rain on one occasion. While the cold front is the replacement of a warm air mass by a cold air mass changing the pressure and creating a thunderstorm in the middle of summer. The warm front happens in zones close to the equator and the cold fronts happen in almost every place.
Hope that helps. x
In 1980 the Mt. St. Helens volcano erupted and impacted thousands of square miles of forest.Some areas are still undergoing secondary succession where
Answer:
Explanation:
1: Pioneer species are the first to colonize: During primary succession in lava on Maui, Hawaii, succulent plants are the pioneer species. After weathering breaks down the lava into the soil, the plants are able to take root. These plants will help to further change the soil by adding nutrients to it.
The first organisms to appear in areas of primary succession are often mosses or lichens. These organisms are known as pioneer species because they are the first species present; pioneer species must be hardy and strong, just like human pioneers.
Of the following elements, which one has the smallest first ionization energy?
A. boron
B. carbon
C. aluminum
D. silicon
Answer:
C. Aluminum
Explanation:
Aluminum has 5.9858 ionization energy
Boron has 8.298 ionization energy
Silicon has 8.1517 ionization energy
Carbon has 11.2603 ionization energy
CH4+4S-CS2+2H2S
how many moles of CS2 can be formed by the complete reaction of 10.6 mol of S
Let's check the equation
[tex]\\ \sf\longmapsto {CH_4\atop 1mol}+{4S\atop 4moles}\longrightarrow {CS_2\atop 1mol}+{2H_2S\atop 2moles}[/tex]
4moles of S gives 1 mol of CS21mol of S gives 1/4=0.25mol of CS210.6mol of S gives:-[tex]\\ \sf\longmapsto 10.6(0.25)=2.65moles\:of\:CS_2[/tex]
Cells of the immune system are able to respond to the
presence of invading organisms because they
recognize the
A) antigens present on the invaders
B) antibodies present in invading pathogens
C) DNA pattern in the nuclei of viruses
D) antibiotics released from microbes
Answer:
A) antigens present on the invaders
Explanation:
Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens. The immune system recognizes and destroys, or tries to destroy, substances that contain antigens
What are some examples of a chemical change? (list more than 2 examples)
Cooking any food.
Burning of wood.
Digestion of food.
Acid-base reaction.
The three nuclides, U-233, U-235, and U-238, are isotopes of uranium because they have the same number of protons per atom and
Answer:
Electrons
Explanation:
Isotopes are atoms which have the same number of protons and electrons but a different number of neutrons. This is also the reason why there are no other changes in the atom but the mass of the specific atom changes.
Hope this helps :)
Merry Christmas. Have fun.
Andrea is making a solution of sweet tea, with 20 grams of sugar dissolved in 180
grams of water. Determine the mass percentage of sugar in the sweet tea.
The mass percentage of sugar in the sweet tea is 10%
From the question,
We are to determine the mass percentage of sugar in the sweet tea
[tex]Mass\ percentage\ of\ sugar\ in\ the\ sweet\ tea = \frac{Mass\ of\ sugar\ in\ the\ solution}{Mass\ of\ the\ solution} \times 100\%[/tex]
Mass of sugar in the solution = 20 g
Mass of the solution = 20g + 180g = 200g
[tex]Mass\ percentage\ of\ sugar\ in\ the\ sweet\ tea = \frac{20}{200} \times 100\%[/tex]
[tex]Mass\ percentage\ of\ sugar\ in\ the\ sweet\ tea = \frac{20}{2} \%[/tex]
∴ Mass percentage of sugar in the sweet tea = 10%
Hence, the mass percentage of sugar in the sweet tea is 10%
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match each statements with the state of matter it describes?
Answer:
Solid liquids , plasma gas
Explanation:
It retains its shape regardless of the shape of the container
What is the source of energy in nuclear weapons?
O A. Combustion
O B. Fusion
O C. Gravity
O D. Fission
Answer:
D. Fission
Explanation:
Induced fission is used to generate nuclear power and for weapons. The products formed during fission gain kinetic energy. It is this energy that is harnessed in nuclear power stations.
2870 j of energy is required to heat and boil one gram of water at 20 °c. how much water at this temperature can 7.14 × 1010 j of energy heat and boil?
Answer:
Explanation:
franchement moi je te dis tu peut le faire tout seul aller bon travaille
The mass of water is equal to 2.48 × 10⁷ g, needs the energy of 7.14 ×10¹⁰ J to heat and boil.
What is the specific heat capacity?The specific heat capacity can be demonstrated as the quantity of energy needed to increase the temperature by one-degree Celcius in one unit of substance.
The temperature will be changed whenever there is a loss or absorption of energy by any substance.
Q = mCΔT
Therefore, there is a direct relationship between the mass of water and the amount of energy.
m ∝ q
[tex]{\displaystyle {\frac{m_1}{m_2} =\frac{q_1}{q_2}[/tex]
[tex]{\displaystyle {m_2} =\frac{q_2}{q_1} \times m_1[/tex]
Given, the energy required to heat mass(m₂) of water, q₂ = 7.14 ×10¹⁰ J
The energy to heat 1 gram of water, q₁ = 2870 J
[tex]{\displaystyle {m_2} =\frac{7.14\times 10^{14}}{2870} \times 1[/tex]
m₂ = 2.48 × 10⁷ g
Therefore, the mass of water is equal to 2.48 × 10⁷ g.
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Which statement below describes the behavior of a Molecules when a substance changes from a gas to liquid
Answer:
As a substance changes from a solid to a liquid to a gas, its molecules first the molecules are moving fast enough, they are able to "escape." They leave the surface of the liquid as gas molecules. Evaporation is not the only process that can change a substance from a liquid to a gas. The same change can occur through boiling.
Explanation:
hopfully this helps!
Which models of the atom in task 1 are not supported by the results of the hydrogen gas experiment? For each of these models, explain the experimental results that the model would predict.
Answer:
Thomson placed two magnets on either side of the tube, and observed that this magnetic field also deflected the cathode ray. The results of these experiments helped Thomson determine the mass-to-charge ratio of the cathode ray particles, which led to a fascinating discovery, minus the mass of each particle was much, much smaller than that of any known atom. Thomson repeated his experiments using different metals as electrode materials, and found that the properties of the cathode ray remained constant no matter what cathode material they originated from. From this evidence, Thomson made the following conclusions:
The cathode ray is composed of negatively-charged particles.
The particles must exist as part of the atom, since the mass of each particle is only ~1/2000 the mass of a hydrogen atom.
These subatomic particles can be found within atoms of all elements.
While controversial at first, Thomson's discoveries were gradually accepted by scientists. Eventually, his cathode ray particles were given a more familiar name: electrons. The discovery of the electron disproved the part of Dalton's atomic theory that assumed atoms were indivisible. In order to account for the existence of the electrons, an entirely new atomic model was needed.
Explanation:
what was johann dobereiner contribution to the periodic table
Answer:
he introduced triads of similar chemical properties in periodic table.
Explanation:
An electron is present at an energy level with an energy of 16.32 x 10−19 J. During a transition to another level, 5.4 x 10−19 J of energy was absorbed. Which of the following is true about the present state of the electron?
Answer Choices:
A. The electron moved down to an energy level and has an energy of 10.92 x 10−19 J.
B. The electron moved down to an energy level and has an energy of 21.72 x 10−19 J.
C. The electron moved up to an energy level and has an energy of 10.92 x 10−19 J.
D. The electron moved up to an energy level and has an energy of 21.72 x 10−19 J.
Answer:
D. The electron moved up to an energy level and has an energy of 21.72 x 10−19 J.
The statement which is true about electrons is that the electron moved up to an energy level and has an energy of 10.92 x 10[tex]^-[/tex]¹⁹ J which is found out as 16.32 x 10[tex]^-[/tex]¹⁹ -5.4 x 10[tex]^-[/tex]¹⁹=10.92 x 10[tex]^-[/tex]¹⁹ J.
What is an energy level?Electrons present in an atom revolve in different orbits which are stationary states and are also called as energy levels. The energy levels are numbered as integers which are also called as principal quantum numbers.
Energy of the stationary state is given as E= -R
1/n² where R
is the Rydberg's constant. When an electron is excited, and it moves from lower to higher energy levels there is absorption of energy, while when it moves from higher energy level to lower energy level it radiates or gives out energy in the form of radiation.
They can also be defined as the distances between electron and nucleus of an atom . Electrons present in K energy level have least energy .Energy level diagrams are studied to understand nature of bonding , placement of electrons in orbits and and elemental behavior under certain conditions.
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Pb2O4 has a ratio of 2:4. It needs to be reduced to?
A.) 1:0
B.) 2:0
C.) 1:2
D.) 2:2
Answer:
C
Explanation:
The reason why is because if you divide 2 by 2 you get 1 and 4 divided by 2 is 2. Hope this helps .
typhoons are more violent than hurricanes
Answer:
i think it is FALSE.
Explanation:
good luck
PLEASE DON'T PUT ANSWER AGAINST GUIDELINES!!!
Answer:
160.3 g S
Explanation: there you go
Melting gold with other metals makes 10 karat gold. Which term best describes 10 karat gold
The 10 karat of gold formed by melting gold with other metals is described as homogeneous mixture.
A pure substance is a substance that is made up of only one kind of particle. This type of substance consist of only one element.
A heterogeneous substance is a type of substance that is made up two or more substances existing in different phases.
A homogeneous substance is a type of substance that is made up of two or more substances evenly mixed. This type of substance exist only in one phase.
Thus, the 10 karat of gold formed by melting gold with other metals is described as homogeneous mixture.
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Answer:
homogeneous mixture
Explanation:
Which of these statements are true? Select all that apply. The Delta. Hf for Br2(I) is 0 kJ/mol. The Delta. Hf for He(I) is 0 kJ/mol. The Delta. Hf for Hg(I) is 0 kJ/mol. The Delta. Hf for Cl2(g) is 0 kJ/mol. The Delta. Hf for N2(I) is 0 kJ/mol.
The enthalpy of formation of liquid mercury and gaseous chlorine are zero because the substance are in their standard state.
The standard state of a substance is the form in which it is found under standard conditions. This include a pressure of 1 atm, a temperature of 298 K and a a concentration of 1 M.
The enthalpy of formation of a substance in its standard state is 0 KJ/mol. The following substances has ΔHf of 0 kJ/mol.
ΔHf of Hg(I) is 0 kJ/mol. ΔHf of Cl2(g) is 0 kJ/molLearn more: https://brainly.com/question/13164491
What type of energy does a person experience when jumping on a trampoline?
A.) elastic potential
B.)all of these
C.) gravitational potential
D.)kinetic
Answer:
Knetic
Explanation:
When you jump on a trampoline, your body has kinetic energy that changes over time. As you jump up and down, your kinetic energy increases and decreases with your velocity. Your kinetic energy is greatest, just before you hit the trampoline on the way down and when you leave the trampoline surface on the way up.
explain why almunium is often used for long distance over head electric cables (high voltage)
Answer:
because it does not cost much and can be found easily. due to their low resistance and excellent conductivity.
Explanation:
Give one example of how environmental factor could influence the way a gene is expressed.
Answer:
The presence of drugs or chemicals in an organisms environment can also influence gene expression in the orgains.
What is the purpose of the chemical ammonia (NH3) in hair dyes?
Answer: Ammonia, an alkaline chemical, is used to raise the pH level (it's levels of acidity) of our hair during the colouring process. This then lifts the cuticles of the hair fibre and allows the colour to be deposited onto the cortex (the inner part of the hair protected by the cuticles). In hair coloring products, ammonium hydroxide is used to support the lightening action of hydrogen peroxide and to prepare hair to accept color pigments. Alkaline properties of ammonia raise the cuticle and allow peroxide and dye molecules to penetrate the hair shaft. (creds to the internet)
Explanation: Hope this helps! :D
Rewrite 5.13467 X 10-6 in correct standard form
isotopes of an element contain different numbers of
Why does potassium have a lower electronegativity than Bromine?
Potassium has a lower EN than Bromine.
EN Trends:
Decreases down the group but increases across a period.
Potassium is to the left of the periodic table while bromine is on the right, and according to the trends, Bromine will be bigger because EN increases across a period. This allows the nucleus to attract the bonding electrons more strongly.
Hope it helps!
What is meant by collision theory?
Answer:
The collision theory states that a chemical reaction can only occur between particles when they collide (hit each other).
hope it helps~
True or false? The empirical formula of a compound is the simplest formula that shows the numerical relationship of the elements in the compound.
Answer:
True
Explanation:
the empirical formula usually shows us the atoms' symbols and then how much of them are present in this certain compound. For example there is H2O
How many grams of CO2 should be placed in a 250 mL container and -24°C to produce a pressure of 95K PA?
Answer:
About 0.53 g of carbon dioxide needs to be added.
Explanation:
Recall the ideal gas law:
[tex]\displaystyle PV = n RT[/tex]
To determine the amount of carbon dioxide we need, we need to solve for n:
[tex]\displaystyle n = \frac{PV}{RT}[/tex]
Recall that P, V, and T are in atm, L, and K, respectively. R is the universal gas constant.
Convert all values into the correct units:
Volume:
[tex]\displaystyle 250\text{ mL } \cdot \frac{1 \text{ L}}{1000 \text{ mL}} = 0.25 \text{ L}[/tex]
Temperature:
[tex]\displaystyle \begin{aligned} K & =( ^\circ C) + 273.15 \\ \\ & = (-24) + (273.15) \\ \\ & = 249 \text{ K}\end{aligned}[/tex]
And pressure:
[tex]\displaystyle 95 \text{ kPa} \cdot \frac{1.00 \text{ atm}}{101.3 \text{ kPa}} = 0.94 \text{ atm}[/tex]
Substitute and evaluate:
[tex]\displaystyle\begin{aligned} n & = \frac{\left(0.94 \text{ atm}\right)\left(0.25 \text{ L}\right)}{\left(\dfrac{0.08206 \text{ L-atm}}{\text{mol-K}}\right)\left(249\text{ K}\right)} \\ \\ & = 0.012 \text{ mol CO$_2$}\end{aligned}[/tex]
Convert moles to grams:
[tex]\displaystyle 0.012 \text{ mol CO$_2$} \cdot \frac{44.01 \text{ g CO$_2$}}{1 \text{ mol CO$_2$}} = 0.53 \text{ g CO$_2$}[/tex]
In conclusion, about 0.53 g of carbon dioxide needs to be added.