The shared ancestry of life is reflected in DNA and genetic code. DNA comparisons can reveal how closely two species are related. Biogeography. Evolution and geological change are reflected in the global distribution of life and the particular characteristics of island species.
What is the oxidation number of each element in PbO2
Answer:
+4
Explanation:
In PbO
2
, oxygen exhibits an oxidation number of −2 (since it's not a peroxide or superoxide).
Let the oxidation number of Pb be x. Then, for the compound to be neutral, the oxidation numbers of all atoms should add up to zero.
⇒x+(−2)+(−2)=0
x=+4
So the oxidation no. of Pb is +4.
The lead (Pb) oxidation number in [tex]\rm PbO_2[/tex] is +4, whereas the oxygen (O) oxidation number is -2.
The idea of oxidation number, also known as oxidation state, is used in chemistry to describe the potential charge that an atom would have if electrons were completely transported in a chemical bond or reaction. It is a valuable instrument for tracking electron distribution in a chemical or ion and understanding redox (oxidation-reduction) reactions. Understanding redox processes, which involve the transfer of electrons between reactants, requires an understanding of oxidation numbers.
Oxidation number of Pb is given as:
(+x) + 2(-2) = 0
x - 4 = 0
x = +4
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Barium nitrate Ba (NO3)2 is used to produce a green colour in fireworks. It is the product of Barium Hydroxide with HNO3. Propose its balanced chemical equation
The balanced chemical equation for the reaction between barium hydroxide, Ba(OH)₂ and HNO₃ to produce barium nitrate, Ba(NO₃)₂ is
Ba(OH)₂ + 2HNO₃ —> Ba(NO₃)₂ + 2H₂O
What is a chemical equation?Chemical equations are representations of chemical reactions using symbols and formula of the reactants and products.
The reactants are located on the left side while the products are located on the right side.
Reactants —> Products
The balancing of chemical equations follows the law of conservation of matter which states that matter can neither be created nor destroyed during a chemical reaction but can be transferred from one form to another.
How to write the balanced equationBa(OH)₂ + HNO₃ —> Ba(NO₃)₂ + H₂O
There are 2 atoms of N on the right side and 1 atom on the left side. It can be balanced by writing 2 before HNO₃ as shown below:
Ba(OH)₂ + 2HNO₃ —> Ba(NO₃)₂ + H₂O
There are 4 atoms of H on the left side and 2 atoms on the right side. It can be balanced by writing 2 before H₂O as shown below
Ba(OH)₂ + 2HNO₃ —> Ba(NO₃)₂ + 2H₂O
Now, the equation is balanced
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How do you feel about GM food?
Answer: I think it's ok, but I have a neutral stance on it.
Explanation: Foods are genetically modified to preserve them and I've had my fair share of wasted money and bad expired food, so I'm a-ok on GM food.
Answer:
Well I think that we should use more for tride or give to our allies
Explanation:
A 6.7 L sample of a gas has a mass of 7.9 g at Standard temperature and pressure. What is the molar mass of the gas?
Round your answer to 2 decimal spaces.
You don't even have to tell me the answer just like an equation or an EXPLANATION!!!!
The molar mass of gas sample whose mass is 7.9g at Standard temperature and pressure is 26.4 g/mol.
How do we calculate molar mass?Molar mass of any substance will be calculated by using the below equation:
M = W/n, where
M = molar mass
W = given mass
n = moles
First we calculate the moles of gas by using the ideal gas equation:
PV = nRT, where
P = standard pressure = 1 atm
V = volume = 6.7 L
n = moles of gas?
R = universal gas constant = 0.082 L.atm/K.mol
T = absolute temperature = 273K
On putting values, we get
n = (1)(6.7) / (0.082)(273)
n = 0.299 moles
Now we get the molar mass of gas by putting values on the first equation, we get
M = 7.9g / 0.299mol = 26.4 g/mol
Hence molar mass of given gas is 26.4 g/mol.
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7. Reproduce the following sentences as indicated in brackets. a. Urmila always goes to temple, .................... ? (Supply the correct question tag) b. The baby was playing with a doll. (Change into interrogative) c. Peter will start a business next year. (Change into "when" question) d. They .............. (not finish)......... the work yet. (Put the verb in the bracket in the correct tense) e. She said to me, "My brother knows you." (Change into indirect speech) f. Ram married Sita. (Change into passive voice)
Answer:
a. Urmila always goes to the temple, doesn't she?
b. Was the baby playing with the doll?
c. When will Peter start a business?
d. They have not finished the work yet.
e. She told me that her brother knows me.
f. Sita was married by Ram.
Explanation:
A. In grammar, a question tag is a very short clause at the end of a statement which changes the statement into a question. For example, in 'She said half price, didn't she?' , the words 'didn't she' are a question tag.
B. Interrogative questions/sentences often have to get a yes/no answer.
C. The "next year" will be the answer to that question. U need to ask when.
D. The have not done the work yet, therefore the answer would change from "not finish" to "have not finished"
E. Indirect speech is speech which tells you what someone said. It's like the game "telephone" indirect speech is what you tell someone else, what another person said, or what someone else tells you what another person said.
F. Passive voice means that a subject is a recipient of a verb's action.
Fill in the missing values in the chart below please. If you can please show your work.
The volume and temperature changes in according to Charles' law will be:
T2 = 363 °CT1 = 869 KV1 = 5.35 LV2 = 144.6 mLWhat is the relationship between volume and temperature of a given mass of gas?The relationship between the volume and temperature of a given mass of gas is given by Charles' Iaw which states that volume is directly proportional to temperature if a gas in Kelvin.
[tex]Mathematically, V_1/T_1 = V_2T_2[/tex]To complete the tables volume and temperature changes:
T2 = 3.5 × (273 +45)/1.75 = 636 K = 363 °CT1 = 35 × 298/12 = 869 KV1 = 250 × 7.6/355 = 5.35 LV2 = 150 × (273 + 24)/(273 + 35) = 144.6 mLTherefore, volume and temperature are directly proportional.
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The attraction forces between mercury atoms in liquid mercury are stronger than the intermolecular forces between water molecules. which of the following is most likely true about mercury? it has a higher surface tension than does water. it exhibits greater capillary action than does water. it is very soluble in water.
The attraction forces between mercury atoms in liquid mercury are stronger than the intermolecular forces between water molecules because it has a higher surface tension than does water.
What is surface tension?Surface tension is the propoerty of the surface of liquids by which they will shrink into the minimum possible surface area.
Surface tension of the liquid mercury is greater than the surface tension of water means cohesive attraction force between the molecules of mercury is greater than water molecules.
Hence option (A) is correct.
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Answer:
It has a higher surface tension than does water.
Explanation:
got it right on edge on 12-15-22
_____AI(NO3)3 + _____NaOH —> ___Al(OH)3
+ _____NaNO3
Answer:
Al(NO3)3 + 3NaOH -----> Al(OH)3 + 3NaNO3
what is the concentration of OH− in a solution with a pOH value of 6.09
Answer:
I'm not sure
Explanation:
I'm just not sure
If a zero order reaction has a rate constant k of 0.0416Mmin and an initial concentration of 2.29 M, what will be its concentration after 20.0 minutes
Answer:
1.46 M
Explanation:
[A]t=−(0.0416 M/min) x (20.0 min)+2.29 M
[A]t=1.46 M
SOMEONE HELP! 100 points have only 2 minutes!
How will different pH levels provide more information?
The neutral phase of a ph scale is 7.
A ph higher than 7 indicates that the substance is basic in nature.
14 is the most basic and 8 is the least basic
A ph lower than 7 indicates the substance is acidic in nature.
1 is the most acidic and 6 is the least acidic.
It’s not a chemistry question but there is no Science Option. Pls help!
Question:
What are some ways we use greenhouse gases and how we can prevent it
What percentage of Earth's land is used for agriculture?
40%
20%
50%
10%
Answer:
40%
Explanation:
hope it helps! God bless
Answer:
40% of Earth's land is used for agriculture.
Toda [4 MARKS] GROUP D: HIGHER ABILITY (HA) 74.2073 Supp. Q.No. 25 केही वस्तुहरूको घनत्व तालिकामा दिइएको छ। उक्त तालिका अध्ययन गरी निम्न प्रश्नहरूको उत्तर दिनुहोस् । (Density of some substance is given in a table. Study the table and answer the following questions:) वस्तु (Substances) घनत्व (Density) X 11 gm/cm Y 8 gm/cm 2Z 0.9 gm/cm i. समान पिण्ड भएका तीनओटा मध्ये सबभन्दा कम आयतन कुन वस्तुको होला ? (Which substance will have least volume if equal masşes of all are taken?) ii. समान आयतन भएका तीनैओटा मध्ये सबभन्दा कम पिण्ड कुन वस्तुको होला ? (Which substance will have the least mass if equal volume of all are taken?) iii. कुन वस्तु पानीमा उविएला ? (Which one will float on water?)
Answer:
Explanation
substance X will have least volume because it has maximum density and using the relation volume inversly propotional to the density of a substance.
substance Z will have least mass beacause it has least density and using relation mass is directly proportional to the volume of a substance .
substance Z will float in water because its density is less than the water (1 gm/cm^3).
What is two masses exerting a force on each other an example of?
Kepler's law
geocentric theory
universal law of gravitation
heliocentric theory
Answer:
universal law of gravitation
Explanation:
According to Newton's law of gravitation, every particle in universe attracts every other particles with a force which is directly proportional to the product of their masses and inversely proportional to the square of distance between their centres!
Consider two particles having masses m1 and m2 and are apart r units, then the gravitational force acting between them is given by
[tex]F = G \cdot \frac{m1\cdot \: m2}{ {r}^{2} } [/tex]
Where G is universal gravitational constant or proportionality constant!!
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62. Write formulas for the following substances and
designate their physical states.
a. nitrogen dioxide gas
b. liquid gallium
c. barium chloride dissolved in water
d. solid ammonium carbonate
The formulas for the substances and designate their physical states as follows:
a. nitrogen dioxide gas NO₂(g)
b. liquid gallium GA (I)
c. barium chloride dissolved in water BaCI₂ (aq)
d. solid ammonium carbonate (NH₄) 2CO₃ (s)
What is chemical formula ?The term chemical formula is defined as an expression that presents the elements in a compound and the relative proportions of those elements.
If only one atom of a particular type is present, no subscript is used. For atoms that have two or more of a particular type of atom present, a subscript is written after the symbol for that atom.
It presents the constituent element and the number of atoms of each element present in one molecule of the compound. It also corresponds to the molecular mass of the compound.
Thus, The formula of nitrogen dioxide gas is NO₂(g).
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The solubility of a gas is 0.890 g/L at a pressure of 120 kPa. What is the solubility of the gas if the pressure is changed to 100 kPa, given that the temperature is held constant?
The solubility of the gas if the pressure is changed to 100 kPa is 0.742 g/L
Effect of Pressure on SolubilityAs the pressure of a gas increases, the solubility increases, and as the pressure of a gas decreases, the solubility decreases.
Thus, Solubility varies directly with Pressure
If S represents Solubility and P represents Pressure,
Then we can write that
S ∝ P
Introducing proportionality constant, k
S = kP
S/P = k
∴ We can write that
[tex]\frac{S_{1} }{P_{1} } = \frac{S_{2} }{P_{2} }[/tex]
Where [tex]S_{1}[/tex] is the initial solubility
[tex]P_{1}[/tex] is the initial pressure
[tex]S_{2}[/tex] is the final solubility
[tex]P_{2}[/tex] is the final pressure
From the given information
[tex]S_{1} = 0.890 \ g/L[/tex]
[tex]P_{1} = 120 \ kPa[/tex]
[tex]P_{2} = 100 \ kPa[/tex]
Putting the parameters into the formula, we get
[tex]\frac{0.890}{120}=\frac{S_{2}}{100}[/tex]
[tex]S_{2}= \frac{0.890 \times 100}{120}[/tex]
[tex]S_{2}= 0.742 \ g/L[/tex]
Hence, the solubility of the gas if the pressure is changed to 100 kPa is 0.742 g/L
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When a liquid is heated, the average (blank) energy of its
particles will increase.
Answer:
trueee is the answer heh need points
When a liquid is heated, the average kinetic energy of its particles will increase.
What is Energy?The ability to do work is called as energy. Work done is product of force and displacement. Energy is of different types as sound energy, kinetic energy, potential energy, electrical energy, light energy etc.
Law of conservation of energy states that energy can neither be created nor destroyed, but it can be transferred from one form to another.
Molecules can move so they show kinetic energy, molecules can be there at many positions so they can show potential energy, molecules can vibrate so they can show sound energy but molecules can only absorb light hence they can't have light energy.
Average kinetic energy = 3KT/2
If temperature increases, kinetic energy also increases.
Therefore, When a liquid is heated, the average kinetic energy of its particles will increase.
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Which substance is beneficial to the aquatic life?
Dissolved Oxygen
Phosphates
Sewage
Plastic
If one 330 mL Coca-Cola contains 170 grams of dissolved C*O_{2} how many H^ + ions are made if 70% of the dissolved C*O_{2} reacts completely with water until it is a simple carbonate ion (CO 3 ^ 2- ) ?
Please help me!!!
Answer:
bu bir kimya sorusu sanırim
what type of chemical reaction is Cu(NO3)2 + NaOH to Cu(OH)2 + NaNO3
Answer:
Cu(NO 3) 2 (aq) + 2 NaOH (aq) → Cu(OH) 2 (s) + 2 NaNO 3 (aq) This is a precipitation reaction: Cu(OH) 2 is the formed precipitate.
Explanation:
In a constant-pressure calorimeter, the temperature of 60.0 g of water increases by 4.50 °C.
What amount of heat is transferred to the water? (Specific heat capacity of water = 4.2 J/gºC)
O A. 7.88 KJ
द
OB. 1.13 KJ
O C. 1.13 J
o D. 7.88 J
The amount of heat transferred to the water if the temperature of 60.0 g of water increases by 4.50 °C is 1.134Kj.
How to calculate heat?The quantity of heat transferred to a substance can be calculated using the following formula:
Q = mc∆T
Where;
Q = quantity of heat (J)m = mass of substancec = specific heat capacity∆T = change in temperatureAccording to the information in this question;
Q = ?m = 60gc = 4.2J/g°C∆T = 4.5°CQ = 60 × 4.2 × 4.5
Q = 1134J
Therefore, the amount of heat transferred to the water if the temperature of 60.0 g of water increases by 4.50 °C is 1.134KJ.
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What is the ph of a solution of h2so4 that has [h3o ] = 5.45 × 10–5 m?
The pH of a solution of sulphuric acid that has hydronium ion concentration is 4.26.
How do we calculate pH?pH of any solution is define as the negative logarithm of the concentration of H⁺ ion present in any solution, i.e.
pH = -log[H⁺]
In the question, it is given that:
Concentration of hydronium ion or H⁺ ion = 5.45×10⁻⁵ M
So, pH will be:
pH = -log(5.45×10⁻⁵)
pH = -(-4.26)
pH = 4.26
Hence required pH is 4.26.
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Distinguish between an acidic and a basic oxide.
(Select all that apply.)
A basic oxide is an oxide that reacts with acids.
An acidic oxide is an oxide that reacts with acids.
In a basic oxide, element forms covalent bonds with oxygen.
In an acidic oxide, element forms ionic bonds with oxygen.
In an acidic oxide, element forms covalent bonds with oxygen.
In a basic oxide, element forms ionic bonds with oxygen.
An acidic oxide is an oxide that reacts with bases.
A basic oxide is an oxide that reacts with bases.
Answer:
an acidic oxide reacts with bases and the seconf
How does colour affect temperature? Provide reasons and must be a few sentences.
Answer:
The more light an object absorbs, the more it heats up when it is exposed to light, which is why dark things get hot more quickly than light things if left out in the sun.
How much water should be added to 85 mL of a 10.0 M stock solution to produce
a 1.0 M dilute solution
765
Explanation:
C1V1=C2V2
10×85=1×V2
V2=850
V'=V2-V2
V'=850-85
V'=765ml
Consider the following oxidation-reduction reaction: 2fe3+(aq) + 2hg(l) + 2cl−(aq) → 2fe2+(aq) + hg2cl2(s). indicate the oxidizing agent and the reducing agent.
Answer:
The reducing agent is Hg (mercury) and the oxidixing agent is Cl (chlorine)
Explanation:
first find the oxidation charges of each of the different ions. All elements that are alone have a charge of 0. As you compare the reactants and products we can see that the chargers of Hg and Cl have changed.
Hg went from a charge of 0 to a charge of +1
Cl went from a charge of 0 to a charge of -1
remember when a substance gains electrons it is reducing and when a substance is losing electrons it is oxidizing.
use the acryonm
OIL
Oxidizing Is Losing
RIG
Reducing Is Gaining
3. Which of the following sentences apply to neutrons? a. have a negative charge. b. circle around the atom nucleus. c. are the only particles that form the nucleus. d. have a mass of 1 amu. SA 2
Answer:
d.have a mass of 1 amu..
Explanation:
Does not match a as the answer for a is electrons B.electron circle around the nucleus because neutrons are inside the nucleus.C.proton and neutrons make the nucleus so the only answer left is .d .which is correct
Answer:c are the only are the only particle that form the nucleus
Explanation:
Question 4 of 10
What effect does adding a solute have on the freezing point of a solution?
A. The solution will not reach a freezing point temperature.
B. The temperature at which the solution freezes is raised.
C. The temperature at which the solution freezes is lowered.
D. The temperature at which the solution freezes is unchanged.
Answer:
C. The temperature at which the solution freezes is lowered.
Look at the screenshots and then answer! Please I need help
Correct answer gets brainlisted :)
Answer:
The first one goes second.
The thirth one goes first,
and the second goes third.
Explanation:
