explain what you understand by valency, give examples
Answer:
Valency is defined as the number of hydrogen atoms which combine directly or indirectly with one atom of an element.
Example:
One atom of nitrogen combines with three atoms of hydrogen to form ammonia gas. So, the valency of nitrogen is 3.
Which of the following correctly describes the role of the mouth in the digestive system?
The mouth acts like a muscular bag by churning the food and producing enzymes that aid in chemical digestion.
The mouth produces all of the enzymes needed for digestion and these enzymes are swallowed, which moves them through the digestive tract.
The mouth begins the process of digestion by mechanically breaking food into smaller pieces.
The mouth performs the peristalsis that pushes food through the rest of the digestive system.
Answer:
The mouth begins the process of digestion by mechanically breaking food into smaller pieces.
Explanation:
Digestion is a crucial process that involves the break down of complex food molecules into simpler ones that are assimilable by the body. The process of digestion in humans, for example, is said to begin in the MOUTH where the food enters through.
The mouth via the use of teeth helps the initially break down the food particles using mechanical/physical method. This further helps the break down of the food into tiny particles before they are acted on enzymatically.
A gas initially has a volume of 300. mL at a pressure of 1.0 atm, what will the
new volume be if the pressure is doubled? (assume constant temperature)
Which represents a balanced nuclear equation?
Describe the trends in properties of chlorides across period 3 .Their formula .Their state .Their volatility .Their structure .The ph of aqueous chloride solution
Answer:
See explanation
Explanation:
Period 3 elements include; Na, Mg, Al, Si, P,S,Cl and Ar
Across the period, the chlorides of the elements change from solid to gas. The chlorides of metals are solid while the chlorides of non metals are gaseous.
Also, the chlorides become more volatile across the period. The formulas of the chlorides change from MCl to MCl2 to MCl3 to MCl4, MCl5 and MCl6 respectively across the period where M is a period 3 element.
The pH of the solutions of chlorides of period 3 elements change from neutral to acidic across the period. The pH of the chlorides of metals are neutral while the chlorides of the nonmetals usually yield acid solutions.
What is the number of carbon atoms in a cycloalkyne with 8 hydrogen atoms
Answer:
4
Explanation:
C4H8
What is the amount of sodium hydroxide, NaOH, in 4.6 g? Use the values given for
the atomic mass of Na, H, and O.
6
Na = 22.989 770 u
H = 1.007 94u
0 = 15.99944
9
a) 0.19 mol
12
b) 0.12 mol
15
c) 1.8 x 102 mol
d) 0.20 mol
Answer: 0.12 Mol
Explanation: Molecular mass of NaOH is = 39,997 g/mol which is Atomic mass of Na + Atomic Mass of H + Atomic mass of O
4.6g / 39.997g/mol = 0.12 mol
1. An atom of an elephant has atomic mass of 39 and has number of neutrons as 20 calculate protons number.
2. An atom of an elephant has the atomic number of 13 and 14 neutrons
A. What is the mass number
B. write the nuclear notation given the atoms as X.
C. How many electrons does atom X have?
D. what is number of protons.
Answer:
See Explanation
Explanation:
1) Let us recall that;
Mass number = number of protons + number of neutrons
Where;
Number of protons = ?
Number of neutrons =20
Mass number =39
Number of protons = mass number - number of neutrons
Mass of protons =39 - 20= 19 protons
2) Atomic number = 13
Number of neutrons =14
Then the mass number =13 +14 =27
The symbol of the element is 27X13
The number of protons= the number of electrons =13
The atomic number is the same as the proton number =13
A seais usually defined as A.A body of freshwater that is not connected to the ocean B. A body of freshwater that is connected to the ocean C. A body of salt water that is not connected to the ocean D. Body of salt water that is connected to the ocean
Answer:
D. Body of salt water that is connected to the ocean
Explanation:
An ocean is a body of salt water which covers approximately 70% of the Earth's surface. About 97% of the Earth's water is comprised of ocean and as such it is the most prominent and defined feature of the Earth. There are basically four (4) categories of an oceanic basin and these are;
1. The Pacific ocean.
2. The Artic ocean.
3. The Atlantic ocean.
4. The Indian ocean.
A sea is usually defined as a body of salt water that is connected to the ocean and are surrounded (enclosed) by land partially.
Basically, a sea is formed where a land and an ocean meet and as a result, an ocean is usually bigger than a sea.
Some examples of seas around the world are Red sea, Mediterranean sea, Sargasso sea, Caribbean sea, Baltic sea, Caspian sea, Chuckchi sea, etc.
Answer:
Yes The Anwer is D Hope This Help:)
What is the energy transformation from wind to usable energy
Answer:
A turbine takes the kinetic energy of a moving fluid, air in this case, and converts it to a rotary motion.
Explanation:
gases have maximum density and rigidity true or false
Answer:
This statement is true.........
Answer:
i think true
Explanation:
Can you please help me with this?
What happens with the evaporation of raindrops in the atmosphere?
Answer:
they become water vapor and after that, they become a type of precipitation
What is Rin the ideal gas law equation?
A. The kinetic energy of the gas
B. The molar mass of the gas
C. The number of moles of the gas
D. The ideal gas constant
Answer:
R is the ideal gas constant
Check all that indicate a chemical change. Check all that apply. Group of answer choices aqueous solutions of silver nitrate and sodium chloride turn cloudy after mixing aqueous solutions of hydrochloric acid and sodium hydrogen carbonate produces bubbles on mixing Sodium hydroxide is mixed with water and the container feels warmer Water is added to orange juice is the color becomes lighter. No answer text provided. ice melts on a bench top at room temperature
Answer:
aqueous solutions of silver nitrate and sodium chloride turn cloudy after mixing aqueous solutions of hydrochloric acid and sodium hydrogen carbonate produces bubbles on mixing Sodium hydroxide is mixed with water and the container feels warmer
Explanation:
A chemical change involves the formation of new substances. Also heat is absorbed or released in a chemical change. Another name for a chemical change is a chemical reaction.
In the first case, a reaction of the sort;
AgNO3(aq) + NaCl(aq) ---> AgCl(s) + NaNO3(aq)
The cloudy solution is due to the formation of AgCl precipitate.
In the second case, a reaction of the sort;
HCl(aq) + NaHCO3(aq) ---> NaCl(aq) + CO2(g) + H2O(l)
The gas evolved is due to the formation of CO2 in the process. Heat is also evolved showing that it is a chemical change.
What is a gas’s temperature in Celsius when it has a volume of 25 L, 203 mol, 143.5 atm?
To Find :
Gas’s temperature in Celsius when it has a volume of 25 L, 203 mol, 143.5 atm .
Solution :
We know, by ideal gas equation :
[tex]PV =nRT\\\\T = \dfrac{PV}{nR}[/tex]
Here, R is universal gas constant and [tex]R = 0.082 \ L \ atm \ mol^{-1} \ K^{1}[/tex]
Putting all given values and R in above equation, we get :
[tex]T = \dfrac{PV}{nR}\\\\T = \dfrac{143.5\times 25}{203 \times 0.082}\ K\\\\T = 215.52\ K[/tex]
Hence, this is the required solution.
where is reverse osmosis used
Answer:
Reverse osmosis systems find frequent use in the following: Boiler feed-water treatment: used to reduce solids content of waters prior to feeding into boilers for power generation or otherwise.
Explanation:
Q1 and Q1 represent ?
Answer:yes they do represent
Help! Locks at 12
Given the balanced equation representing a nuclear reaction:
Which particle is represented by X?
Answer is #4 (neutrons)
Explanation:
Total mass before the reaction is 236 amu. The total mass of the two elements is 233 amu. This means that there are 3 amus carried by element X. Looking at the total atomic number of the two elements after reaction, it's 92, the same as the one at the beginning. This means that element X has zero atomic number, which could only be a neutron.
Answer: is 4
Explanation:
I was doing the same one
A mixture of gases with a pressure of 900 mm Hg contains 20% of oxygen and 80% of nitrogen by volumeWhat is the partial pressure of the oxygen gas in the mixture?
A-45mmHg
B-180mmHg
C-210 mmHg
D-320 mmHg
Answer:
180 mmHg
Explanation:
Total volume of gases = 20% + 80%= 100%
Total pressure of gases = 900 mm Hg
Note that partial pressure of a gas = mole fraction × total pressure
Mole fraction of oxygen = 20/100
Hence partial pressure of oxygen= 20/100 × 900 mm Hg
partial pressure of oxygen= 180 mmHg
Perform the following
mathematical operation, and
report the answer to the
correct number of significant figures.
7.68 x 4.564 = [?]
Answer: The correct number of significant figures in [tex]7.68 \times 4.564[/tex] is 35.05152.
Explanation:
Digits present in a number that helps in determining the degree of accuracy starting from the first non-zero digit is called a significant figure.
Some rules for significant figures are as follows.
All the digits present within the non-zero digits are considered in a number.For example, 2085 contains 4 significant digits.
Leading zeros are not counted in a number.For example, 0.0034 has 2 significant digits.
We count the trailing zeros when a decimal point is present in a number.For example, 0.02500 has 4 significant figures.
When there is no decimal point then trailing zeros may or may not count.For example, 19000 has 2 significant digits.
Now, the product of given digits is as follows.
[tex]7.68 \times 4.564 = 35.05152[/tex]
Thus, we can conclude that correct number of significant figures in [tex]7.68 \times 4.564[/tex] is 35.05152.
NEED HELP!! See picture for question!
Answer: The answer is A.
How many moles are in 50 grams of CO2?
Answer:
The answer is 44.0095. We assume you are converting between grams CO2 and mole.
I hope it help you
Plzzzzzzzzzzzzzzzz can you follow me please
two types of fine chemical
Answer:
Flavors and fragrances
if 5.0g zinc reacts with 10.0 g hci to produce h2 gas and znci2 according to the following equation zn=2hci znci2 + h2 what is the limiting reactant and how many grams of h2 will be produced
Answer: The mass of [tex]H_2[/tex] produced is 0.153 g
Explanation:
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
For zinc:Given mass of zinc = 5.0 g
Molar mass of zinc = 65.38 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of zinc}=\frac{5.0g}{65.38g/mol}=0.0765mol[/tex]
For HCl:Given mass of HCl = 10.0 g
Molar mass of HCl = 36.46 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of HCl}=\frac{10.0g}{36.46g/mol}=0.274mol[/tex]
The given chemical equation follows:
[tex]Zn+2HCl\rightarrow ZnCl_2+H_2[/tex]
By stoichiometry of the reaction:
If 1 mole of zinc reacts with 2 moles of HCl
So, 0.0765 moles of zinc will react with = [tex]\frac{2}{1}\times 0.0765=0.153mol[/tex] of HCl
As the given amount of HCl is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.
Thus, zinc is considered a limiting reagent because it limits the formation of the product.
By the stoichiometry of the reaction:
If 1 mole of zinc produces 1 mole of [tex]H_2[/tex]
So, 0.0765 moles of zinc will produce = [tex]\frac{1}{1}\times 0.0765=0.0765mol[/tex] of [tex]H_2[/tex]
We know, molar mass of [tex]H_2[/tex] = 2 g/mol
Putting values in above equation, we get:
[tex]\text{Mass of }H_2=(0.0765mol\times 2g/mol)=0.153g[/tex]
Hence, the mass of [tex]H_2[/tex] produced is 0.153 g
i need help asap please :) it says to “identify the reactants.”
the options are
A: Carbon Dioxide and water
B: Glucose and oxygen
C: sunlight and chlorophyll
The reactants are A: Carbon Dioxide and water
What is the energy of a photon that emits a light of frequency 6.42 x 1014 Hz?
Answer:
Option B. 4.25×10¯¹⁹ J
Explanation:
From the question given above, the following data were obtained:
Frequency (f) = 6.42×10¹⁴ Hz
Energy (E) =?
Energy and frequency are related by the following equation:
Energy (E) = Planck's constant (h) × frequency (f)
E = hf
With the above formula, we can obtain the energy of the photon as follow:
Frequency (f) = 6.42×10¹⁴ Hz
Planck's constant (h) = 6.63×10¯³⁴ Js
Energy (E) =?
E = hf
E = 6.63×10¯³⁴ × 6.42×10¹⁴
E = 4.25×10¯¹⁹ J
Thus, the energy of the photon is 4.25×10¯¹⁹ J
Answer:
B. 4.25 x 10-19J is correct via a p e x
Explanation:
Write a neutralization reaction to form the salt k2so4
H2SO4 + 2KCL ----------› K2SO4 + 2HCL
hope it helps you ♡♡
I'll give brainliest. My group has been struggling to answer this. We just need a solid answer with work to pick up our grades at least.
How many grams of Al(OH)3 are produced from 3.00 g of AlCl3 with excess of NaOH?
Explanation:
here u go the Answer with the working:)
how many types of kinetic energies are there? is it 4 or 5 types?
Calculate the molality of a solution that contains 51.2 g of naphthalene, C10H8, in 500 mL of carbon tetrachloride. The density of CCl4 is 1.60 g/mL.
Answer: The molality of naphthalene solution is 0.499 m
Explanation:
Density is defined as the ratio of mass and volume of a substance.
[tex]\text{Density}=\frac{\text{Mass}}{\text{Volume}} [/tex] ......(1)
Given values:
Volume of carbon tetrachloride = 500 mL
Density of carbon tetrachloride = 1.60 g/mL
Putting values in equation 1, we get:
[tex]\text{Mass of carbon tetrachloride}=(1.60g/mL\times 500mL)=800g[/tex]
Molality is defined as the amount of solute expressed in the number of moles present per kilogram of solvent. The units of molarity are mol/kg. The formula used to calculate molarity:
[tex]\text{Molality of solution}=\frac{\text{Given mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Mass of solvent (in g)}}[/tex] .....(2)
Given values:
Given mass of naphthalene = 51.2 g
Molar mass of naphthalene = 128.17 g/mol
Mass of solvent = 800 g
Putting values in equation 2, we get:
[tex]\text{Molality of naphthalene}=\frac{51.2\times 1000}{128.17\times 800}\\\\\text{Molality of naphthalene}=0.499m[/tex]
Hence, the molality of naphthalene solution is 0.499 m
