chemistry class 9 chapter 1​

Answer:

O B. Convert the 10 g of NaCl to moles of NaCl.

Explanation:

The formula for finding the molality is m=moles of solute/kg of solvent. The solute for this question is NaCl and the solvent is water.

(10g NaCl)(1 mol NaCl/58.44g NaCl)=0.1711 mol NaCl

58.44 is the molar mass of NaCl

m=0.1711 mol NaCl/2 kg H2O

m=0.085557837

the universe formed through the big bang explosion, all of the elements on Earth have been cooked for billions of years in stars and then released in the universe through super- nova explosions.

Answer:

Hydrogen bromide, anhydrous appears as a colorless gas with a pungent irritating odor. Corrosive. Heavier than air. Prolonged exposure to fire or intense heat may result in the violent rupture and rocketing of the container. Long-term exposure to low concentrations or short-term exposure to high concentrations can result in adverse health effects from inhalation. Used to make other chemicals and as a catalyst in the manufacture of chemicals. Rate of onset: Immediate Persistence: Minutes to hours Odor threshold: 2 ppm Source/use/other hazard: Chemical manufacturing industry; very corrosive.

Explanation:

HBr

D. The MOLARITY of the juice DECREASES when water is added to it.

MOLARITY refers to the amount of a substance (solute) in a certain volume of solution. It is a measure of the CONCENTRATION OF A SOLUTION. In chemistry, molarity is calculated by dividing the number of moles of a solute by the volume of the solvent i.e.

MOLARITY (mol/L or M) = number of moles (n)/volume of solvent (V)

* The above equation means that the molarity of a solution is inversely proportional to its volume i.e. as molarity increases, volume decreases and vice versa.

According to this question, water is added to a glass of pure fruit juice (dilution). This means that the volume of the juice will increase. As the volume increases via addition of water, the MOLARITY DECREASES.

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Answer:

electrons are knocked off atoms, causing electricity to flow.

Explanation:

Answer:

82 °C

Explanation:

Let the specific heat capacity of the coffee be that of water which is 4.2 J/g °C.

Now, at the final temperature, heat gained by Aluminum spoon ,Q equals heat lost by coffee, Q'.

Q = -Q'

Q = m₁c₁(T₂ - T₁) where m₁ = mass of aluminum spoon = 45 g, c₁ = specific heat of aluminum = 0.88 J/g °C, T₁ = initial temperature of aluminum spoon = 24 °C and T₂ = final temperature of aluminum spoon.

Q' = m₂c₂(T₂ - T₃) where m₂ = mass of coffee = 180 g, c₂ = specific heat of coffee = 4.2 J/g °C, T₃ = initial temperature of coffee = 85 °C and T₂ = final temperature of coffee.

So, Q = -Q'

m₁c₁(T₂ - T₁) = -m₂c₂(T₂ - T₃)

Making T₂ subject of the formula, we have

m₁c₁T₂ - m₁c₁T₁ = -m₂c₂T₂ + m₂c₂T₃

m₁c₁T₂ + m₂c₂T₂ =  m₂c₂T₃ + m₁c₁T₁

(m₁c₁ + m₂c₂)T₂ =  m₂c₂T₃ + m₁c₁T₁

T₂ =  (m₂c₂T₃ + m₁c₁T₁)/(m₁c₁ + m₂c₂)

substituting the values of the variables into the equation, we have

T₂ =  (180 g × 4.2 J/g °C × 85 °C + 45 g × 0.88 J/g °C × 24 °C )/(45 g × 0.88 J/g °C  + 180 g × 4.2 J/g °C)

T₂ =  (64260 J + 950.4 J)/(39.6 J/°C  + 756 J/°C)

T₂ =  65210.4 J/795.6 J/°C

T₂ =  81.96 °C

T₂ ≅  82 °C

Answer:

Explanation:

6.         p⁺      e⁻

Ca²⁺    20     18

F⁻          9      10

O²⁻        8      10

Na⁺       11      10

7. Physical properties of matter are properties that can be measured or observed without matter changing to an entirely different substance. These include odor, boiling point, melting point, density, electrical conductivity and heat conductivity.

Separation of mixture:

Chromatography involves solvent separation on a solid medium.

Distillation takes advantage of differences in boiling points.

Evaporation removes a liquid from a solution to leave a solid material.

Filtration separates solids of different sizes.

Funnel partitioning with solvents. Solvent dissolves one component but not the other.

8.Bulk Elements => Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur & Phosphouous

Microminerals are those minerals needed in less than 100 mg quantities. Trace minerals or trace elements are usually needed in microgram quantities. Microminerals include iron, zinc, copper, iodine, fluoride, chromium, cobalt, selenium, manganese, and molybdenum.

Diatomic Molecules => H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂

9. Electron Configurations

    Na: 1s²2s²2p⁶3s¹ => valence = 3s¹

    N:   1s²2s²2p³ => valence = 2s²2p³

    Al:  1s²2s²2p⁶3s²3p¹ => valence = 3s²3p¹

Valence is the highest principle quantum number (or, principle energy level  ~ ring) in the electron configurations.

10.moles of glucose = 450g/180.16 g/mol =2.50 moles

   C₂H₆O₂ = 2(12) + 6(1) + 2(16) = 24 + 6 + 32 = 62 g/mole

Answer:

Radiometric dating or radioactive date is the method that uses radioisotope to date the formation of a rock. The age of the rocks will be determined.

Explanation:

Radioactive deterioration is a natural process and results from the unstable atomic core, which releases bits and parts.

These radioactive particles are released as (there are many types). This decline process results in a more equilibrated nucleus, which makes the atom stable when the number of protons and neutrons balances.

This radioactivity is suitable for dating, as a radioactive "parent" item is constantly decaying into a stable "daughter" element.

A single mineral grain or a whole rock may be dated. There are techniques by which the sample is excited in a nuclear reactor and then measured with a mass spectrometer. The isotope (such as in the argon-argon scheme).

Others put mineral grains under a special microscope, fir in the grains with an ionising laser beam that releases the mineral and the isotopes.

The isotopes are measured by a mass spectrometer inside the same machine (an example of this is SIMS analysis).

Answer:

Plastic pollution are harmful on land because;

Answer:

the atomic number decreased in 2, from 100 to 100 - 2 = 98. 3) Hence the formed atom has atomic number 98, which is californium, Cf, and the isotope is californium - 253. 4) The item that completes the given alpha decay reaction is: ₉₈²⁵³ Cf.

Explanation:

Answer:

Between galaxies, retake the measurement.

Explanation:

Among both galaxies, reiterate the measurements. Instead of utilising a balloon, a scientist might create a model that shows in which everything really is and how cosmos is expanding rather than expanding. By inflating up the atmosphere to 1/2, 3/4, and full size, continue the operation.

Answer:

B. Lithium (Li) and iodine (1)

Explanation:

Ionic bond is a type of chemical bond that is formed between a metallic element and a non metallic element. The positive charge of the metallic ion is attracted to the negative charge of the non metallic ion to form an ionic bond.

According to the options given in this question, lithium and iodine will form an IONIC bond because lithium is a cation (+ve ion) while iodine is an anion (-ve).

Isotopes are atoms of the same element that have different masses. The relative atomic mass (am) is a weighted average that takes into account the abundance of each isotope. We can calculate the relative atomic mass using the following expression.

[tex]am = \frac{\Sigma m_i \times ab_i}{100}[/tex]

where,

For Gallium,

[tex]70.59 amu = \frac{69 amu\ x + 71 amu\ y}{100}[/tex]     [1]

where "x" and "y" are the unknown abundances.

We also know that the sum of both abundances must be 100%.

x + y = 100

y = 100 - x   [2]

If we replace [2] in [1], we get

[tex]70.59 amu = \frac{69 amu\ x + 71 amu\ (100-x)}{100} \\7059 amu = -2 amu\ x + 7100amu \\x = 20.5[/tex]

Then, in [2]

y = 100 - x = 100 - 20.5 = 79.5

In conclusion, Ga-69 has an abundance of 20.5% and Ga-71 has an abundance of 79.5%.

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Answer:

chlorine Will be at highest

IF NOT THEN SORRY :)

Answer:

This is true.

Explanation:

R should be 0.0821

Good luck!

Answer: Volatile compounds present in the fresh sage leaf or mint leaf evaporate on rubbing.

Explanation:

When fresh sage or mint is rubbed on the skin or any other surface the volatile chemicals associated with the integral structure of the plant part get evaporated in the surrounding air and the vapors can be detected by the olfactory receptors present in the nose. These receptors take the smell or fragrance stimulus and generate impulses or signals which goes to brain and brain interprets the smell or fragrance.

Answer:

17

Explanation:

i need points

Answer:

About bonding

Explanation:

A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bond.

Answer:

An ionic bond occurs between sodium and chlorine where sodium has one  electron while chlorine has seven electrons. The electron from sodium is lost and transferred to a chlorine atom which results in a sodium ion with a charge of one+ and a chloride ion with a charge of one-. These oppositely charged ions attract each other making a balanced charge to make a compound that is electrically neutral.. Sodium cation (Na+) and chlorine anion (Cl-) are attracted to each another to form sodium chloride (table salt). When dissolved in water, the sodium and chloride ions are strongly attracted to the polar water molecules because of ion-dipole interactions.  

Explanation:

Answer:

yes

Explanation:

because is smallest element that are made up of atom

Answer: Yes

Explanation:

ayo thanks mate :0000000000000000000000

B because decomposition reactions are often caused by the application of heat to break up the bonds within the molecules, which will form the molecules that made up the decomposed molecule.

Answer:

atom is electrically neutral because

the no.of protons is equal to no.of

electrons.

Therefore the negative charge and

positive charge cancels out.

Answer:

the group with helium at the top

Explanation:

I just took it

Answer:

Explanation:

Element -

It is the basic unit of matter, which cannot be broken down into substances by any way but can be combined to form new substances.

It is a pure substance.

It classifies into metals, non-metals, metalloids and noble gases.

Example - Hydrogen, Carbon, Oxygen

Compounds -

It is a combination of two or more elements.

It is a pure substance.

Through chemical reactions, they can be broken down into metals.

Example - Water, Carbon dioxide

Mixtures -

It is a combination of two or more elements or compounds or both.

The substances combined in a mixture are in a particular ratio.

Example - Chalk powder, Washing Soda

Answer:

of what grade it is of??

Explanation:

tell me then ill answer