How were the elements in the first periodic table arranged? O A. In order of atomic number B. Alphabetically by element name C. In order of date of discovery O D. In order of atomic mass
Answer:
in order of their atomic mass
The first periodic table created by Mendeleev was based on the atomic masses of elements. Later Mosely modified it based on the atomic number.
What is periodic table ?Periodic table is the classification of all the known elements based on their atomic number. There are 118 elements in periodic table now. They are classified into different groups and periods.
Mendeleev was first to create periodic table for the easy classification of elements. He classified elements based on their atomic masses. At that time there were only 60-65 elements discovered.
Later Mosley modified it to modern periodic table based on the increasing order of atomic number of elements. Therefore, the first arrangement was based on atomic masses.
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Automobile airbags inflate due to the formation of nitrogen gas from the chemical reaction 2NaN3(s)—> 3N2(g)+2Na(s) Identify the number of each atom in the reactants and products for this balance reaction.
why are metal containers not used for storing acids
Metal containers are not used for storing acid because most of the time acid reacts with almost every metal and produces salts or oxides which alters the acid characteristics making it useless....
Calculate the molecular weight of a dibasic acid.0.56gm of which is required 250ml of N/20 sodium hydroxide solution for neutralization.
Answer: The molecular weight of the dibasic acid is 89.6 g/mol
Explanation:
Normality is defined as the amount of solute expressed in the number of gram equivalents present per liter of solution. The units of normality are eq/L. The formula used to calculate normality:
[tex]\text{Normality}=\frac{\text{Given mass of solute}\times 1000}{\text{Equivalent mass of solute}\times \text{Volume of solution (mL)}}[/tex] ....(1)
We are given:
Normality of solution = [tex]\frac{1}{20}=0.05N[/tex]
Given mass of solute = 0.56 g
Volume of solution = 250 mL
Putting values in equation 1, we get:
[tex]0.05=\frac{0.56\times 1000}{\text{Equivalent mass of solute}\times 250}\\\\\text{Equivalent mass of solute}=\frac{0.56\times 1000}{0.05\times 250}=44.8g/eq[/tex]
Equivalent weight of an acid is calculated by using the equation:
[tex]\text{Equivalent weight}=\frac{\text{Molar mass}}{\text{Basicity}}[/tex] .....(2)
Equivalent weight of acid = 44.8 g/eq
Basicity of an acid = 2 eq/mol
Putting values in equation 2, we get:
[tex]44.8g/eq=\frac{\text{Molar mass}}{2eq/mol}\\\\\text{Molar mass}=(44.8g/eq\times 2eq/mol)=89.6g/mol[/tex]
Hence, the molecular weight of the dibasic acid is 89.6 g/mol
Write two points of differences between complete and incomplete combustion?
Answer:
In complete combustion, there is a sufficient supply of oxygen which is able to react with the burning hydrocarbon allowing the reaction products H2O and CO2 to be formed. In incomplete combustion there is a lack of oxygen so when heat is applied carbon monoxide is released.
I hope this will help you......
how does liquid carbon dioxide connect to organic chemistry
please I need long answers
1.25 X 10^24 molecules of chlorine gas react with sodium to form how many grams of sodium
chloride?
2Na + Cl2
--> 2NaCl
Answer:
241.28 g NaCl(s)
Explanation:
Given 1.25 x 10²⁴ molecules of Cl₂ = 1.25 x 10²⁴molecules Cl₂(g)/6.023 x 10²³ molecules/mole = 2.08 mole Cl₂(g)
2Na(s) + Cl₂(g) => 2NaCl(s)
excess 2.08mole ? mole
∴moles NaCl(s) formed from 2.08 moles Cl₂(g) = 2(2.08 mole NaCl(s))
= 4.16 mole NaCl(g) = 4.16 mole NaCl(s) x 58 g NaCl(s)/mole NaCl(s) = 241.28 g NaCl(s)
In an electrically neutral atom, the number of
protons equals the number of neutrons.
protons equals the number of electrons.
neutrons equals the number of electrons.
A. Protons equals the number of neutrons
B. Protons equal the number of electrons
C. Neutrons equals the number of electrons
Answer: B
Answer:
B
Explanation:
because protons have a +1 charge and electrons have a -1 charge, so if an atom is neutral it must have the same amount of protons and neutrons
Which of the compounds listed below would be considered ionic?
options:
NO2
P4S3
NiCl2
SO3
Nothing listed can be classified as an ionic substance.
Answer:
NICL2 are classified as an ionic substance
what do you mean by thick pile of volcanic materials??
Answer:
You should repent God is coming back soon
Which is producer gas? a) CO+H2 b) CO+N2 c) CO+ O2 d) CO+H20
Answer:
co + H2 it is the answer may it helpfull
Answer:
d
Explanation:
because CO mixes with H2O
What is one characteristic that makes Earth capable of supporting life?
A. It has ocean currents that circulate water from pole to pole.
O B. It has a strong magnetic field that protects organisms from
harmful radiation.
C. It is in a solar system located in one of the outer arms of a spiral
galaxy
D. It has more mass than any of the other planets of the inner solar
system.
Answer:
it is option (d)
it has more mass than any of the other planets of the inner solar system
How many grams of Br are in 345g of CaBr2?
Answer:
276g of Br are present
Explanation:
To solve this question we need to find the moles of CaBr2 using its molar mass -CaBr2: 199.89g/mol-. As 1 mole of CaBr2 contains 2 moles of Br we can find the moles of Br and its mass:
Moles CaBr2:
345g * (1mol/199.89g) = 1.7259 moles CaBr2
Moles Br:
1.7259 moles CaBr2 * (2mol Br / 1mol CaBr2) = 3.4519 moles Br
Mass Br -Molar mass: 79.904g/mol-
3.4519 moles Br * (79.904g/mol) = 276g of Br are present
Si 40 g de un compuesto C6H10O5 se disuelven en 500 g de agua, determine el punto de ebullición de esta solución. (Agua: temperatura de ebullición 100 °C y Ke = 0,52 °C/m)
The question is: If 40 g of a compound C6H10O5 are dissolved in 500 g of water, determine the boiling point of this solution. (Water: boiling temperature 100 ° C and Kb = 0.52 ° C / m).
Answer: The boiling point of given solution is [tex]100.256^{o}C[/tex].
Explanation:
Given: Mass of solute = 40 g
Mass of solvent = 500 g (1 g = 0.001 kg) = 0.5 kg
[tex]K_{b} = 0.52^{o}C/m[/tex]
Molality is the moles of solute present in kg of solvent.
Moles is the mass of substance divided by its molar mass. Hence, moles of [tex]C_{6}H_{10}O_{5}[/tex] (molar mass = 162.141 g/mol) is calculated as follows.
[tex]Moles = \frac{mass}{molar mass}\\= \frac{40 g}{162.141 g/mol}\\= 0.246 mol[/tex]
Now, molality of the solution is calculated as follows.
[tex]Molality = \frac{molesof solute}{mass(in kg)}\\= \frac{0.246}{0.5 kg}\\= 0.492 m[/tex]
The boiling point is calculated as follows.
[tex]\Delta T_{b} = K_{b}m[/tex]
where,
m = molality
Substitute the values into above formula as follows.
[tex]\Delta T_{b} = K_{b}m\\= 0.52^{o}C/m \times 0.492 m\\= 0.256^{o}C[/tex]
As the boiling point of water is 100 degree Celsius. So, the boiling point of solution is as follows.
[tex](100 + 0.256)^{o}C\\= 100.256^{o}C[/tex]
Thus, we can conclude that the boiling point of given solution is [tex]100.256^{o}C[/tex].
Which of the following contains the greatest mass of oxygen?
A
1 mole of oxygen gas, 02
B
1.8 mole of oxygen atoms
C
30 g of oxygen gas
D
3.01 x 1024 atoms of oxygen
Answer:
letter d
Explanation:
hope it's help you
At a temperature of -25 °C, a sample of gas in a rigid container exerts a pressure of 55.8 kPa. At what temperature will the pressure reach 145 kPa?
The required temperature of the gas sample is -64.96 °C.
What is ideal gas equation?Ideal gas equation gives idea about the behavior of gas at different condition & represented as:
PV = nRT.
From the above equation it is clear that relation between temperature and pressure for this question is:
P₁/T₁ = P₂/T₂, where
P₁ & T₁ are the initial pressure and temperature.
P₂ & T₂ are the final pressure and temperature.
On putting values, we get
T₂ = (145)(-25) / (55.8) = -64.96 °C
Hence required temperature of the sample is -64.96 °C.
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a) The bubbles must be negatively charged.
b) The bubbles must be positively charged.
c) The bubbles must have the opposite charge to the charge on the student.
d) The bubbles must have the same charge as the charge on the student.
Answer:
C
Explanation:
like charges repel each others so if they have the same charge they will move away from each other
The reaction from NaOH and CH3COOH gives
a. Basic Salt
b. Acidic Salt
c. Normal Salt
d. Neutral Salt
As Danny was pouring cereal for his breakfast, he noticed that the cereal box says that the cereal contains 5 milligrams of iron per serving. Danny decided to perform an experiment to test this claim. He found that the cereal contains 4.6 milligrams of iron per serving. Based on Danny's measurement, the value reported on the label is because .
The question is incomplete, the complete question is;
As Danny was pouring cereal for his breakfast, he noticed that the cereal box says that the cereal contains 5 milligrams of iron per serving. Danny decided to perform an experiment to test this claim. He found that the cereal contains 4.6 milligrams of iron per serving. Based on Danny's measurement, the value reported on the label is ( CORRECT OR INCCORECT) because A: (IT IS DIFFERENT FROM THE VALUE DANNY MEASURED) B: (IT IS REORTED TO THE NEAREST MILLIGRAM) C: (IT USES THE SAME UNITS THAT DANNY USED).
Answer:
CORRECT because IT IS REORTED TO THE NEAREST MILLIGRAM
Explanation:
In mathematics, values may be rounded up or down as required. In the case of this measurement of cereals by Danny, it is customary to measure the amount of iron per serving to the nearest milligram.
As such, even though Danny found out that the actual amount of iron per serving in the cereal is 4.6 milligrams, the value reported on the cereal box is still correct because it was reported to the nearest milligram hence the value had to be rounded up.
How do you express a number in scientific notation?
A. Write the number as a fraction in a scientific equation
B. Write the number along with the units associated with it
C. Write the number in units of Avogadro's number
D. Write the number as a decimal multiplied by a power of 10
SUBMIT
Can someone please do 5, 6, 8, 10
Read the temperatures shown to the nearest 0.5°C.
I’ll mark you as brainlister
Answer:
The temperature to the nearest 0.5°C is 98.5°C
the representative particle for KBr is the?
Answer:
This is a chemical symbol for Potassium Bromide
The reaction of an alkene and water in the presence of an acid catalyst to produce an alcohol is called ________.
MATCH THE FOLLOWING:
1.rayon. a. Thermocol
2.teflon. b. Mattresses
3.acrylic. c. Dress material
4.polycot. d. Nonstick cookware
5.polyurethane. e. syntheticknittingwool
6.polystyrene. f.Blended dress material
I don't know
I don't know
I don't know
I don't know
The reversible reaction, 4HCl(g) + Si (s) ⇌ SiCl4 (l) + 2H2 (g) , would be classified as a ______________ reaction.
exothermic
endothermic
homogeneous
heterogeneous
Answer:
endothermic
Explanation:
endothermic reactions absorb heat from their surroundings, in this reaction the reactants are gas and solid and the products are liquid and gas, implying heat was absorbed to turn a solid to a liquid.
define all the physical features of earth
MOUNTAINS
Mountains are large, tall, and elevated land areas on the earth's surface. They have steep, sloping sides and sharp or rounded ridges, and a high point, called a peak.
PLAINS
Plains are one of the major landforms on earth. They are areas of flat lands.
PLATEAUS
A plateau is a flat, elevated landform that rises above the surrounding area.
DESERTS
Regions of dry, arid lands.
DELTAS
A river delta is a landform created by deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water.
If the elements W, X, Y, and Z have electronegativity values of 1.0, 2.0, 2.5, and 3.5, respectively, which bond is the least polar
Answer:
XY bond is the least polar
Explanation:
Given
[tex]W = 1.0[/tex]
[tex]X = 2.0[/tex]
[tex]Y = 2.5[/tex]
[tex]Z = 3.5[/tex]
Required
The least polar bond
First, we calculate the difference in the electronegativities
[tex]WX = X - W[/tex]
[tex]WX = 2.0 - 1.0[/tex]
[tex]WX = 1.0[/tex]
[tex]WY = Y - W[/tex]
[tex]WY =2.5 - 1.0[/tex]
[tex]WY =1.5[/tex]
[tex]WZ =Z-W[/tex]
[tex]WZ =3.5 - 1.0[/tex]
[tex]WZ =2.5[/tex]
[tex]XY = Y -X[/tex]
[tex]XY = 2.5 -2.0[/tex]
[tex]XY = 0.5[/tex]
[tex]XZ = Z -X[/tex]
[tex]XZ = 3.5 -2.0[/tex]
[tex]XZ = 1.5[/tex]
[tex]YZ = Z - Y[/tex]
[tex]YZ = 3.5 - 2.5[/tex]
[tex]YZ = 1.0[/tex]
The least of the above calculations will be the least polar.
Hence, XY is the least polar
Balance the equation for
__Ca+__Pb(NO3)2—__Pb+__Ca(NO3)2
Answer:
Ca + Pb(NO3)2 → Pb + Ca(NO3)2
Explanation:
This is an oxidation-reduction (redox) reaction:
PbII + 2 e- → Pb0
(reduction)
Ca0 - 2 e- → CaII
(oxidation)
Pb(NO3)2 is an oxidizing agent, Ca is a reducing agent.
What does binding energy measure?
A. The forces attracting electrons to a nucleus
B. The repelling forces pushing protons apart
C. The energy used to hold the nucleus together
D. The energy released in radioactive decay
Answer:
C. the energy used to hold the nucleus together
