i really need help please

Answer:

The valency of a molecule is zero.

Explanation:

Valency is calculated by calculating number of electrons present in outermost orbitals of atom of element.

Answer:

C and D

Explanation:

A reaction is said to be decomposed, if the reactant is broken down to liberate single element.

When NaCl is added to a solution of AgNO₃, Pb(NO₃)₂, or Ca(NO₃)₂,a precipitate will form only in Ca(NO₃)₂ only.

In a double displacement reaction, the reacting substances exchange their ions or bonds and form new compounds

In a double displacement reaction, only ionic compounds can take part and  compounds of only those metal reacts which will be almost having equal reactivity.

For example -

Sodium chloride can react with Potassium sulphate to form Sodium sulphate and Potassium chloride.

Barium nitrate can react with Lead sulphate to form Barium Sulphate and Lead nitrate.

Therefore, When NaCl is added to a solution of AgNO₃, Pb(NO₃)₂, or Ca(NO₃)₂,a precipitate will form only in Ca(NO₃)₂ only.

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Answer:

1)physical change

Explanation:

2)chemical change

Nguyên tố hóa học, thường được gọi đơn giản là nguyên tố, là một chất hóa học tinh khiết, bao gồm một kiểu nguyên tử, được phân biệt bởi số hiệu nguyên tử, là số lượng proton có trong mỗi hạt nhân.

Answer:

Friction always slows a moving object down. ... Friction can be a useful force because it prevents our shoes slipping on the pavement when we walk and stops car tyres skidding on the road. When you walk, friction is caused between the tread on shoes and the ground. This friction acts to grip the ground and prevent sliding.

Explanation:

group 1 elements reacts with oxygen

Answer:

Historically,Tamil Nadu is known for its temple tanks and community tanks that not only save water for summer but also act as artifical ground water recharge structures. It also set an example by making rain water harvesting mandatory in all building. But now water crisis associated with monsoon failure for consecutive years had lead it to a desperate situation.

Answer:

?

Explanation:

did you mean kilograms?

Los elementos que forman aniones con carga -1 y una capa externa estable de ocho electrones pertenecen al grupo de los: halógenos.

Para alcanzar la estabilidad, los átomos siguen la regla del octeto: ganan, pierden o comparten electrones para tener 8 electrones en su capa externa (capa de valencia).

Los elementos del Grupo 17 de la Tabla Periódica, conocidos como halógenos, tienen 7 electrones en su capa de valencia. Así, tienden a ganar 1 electrón para completar su octeto. Como los electrones tienen carga negativa, al ganar 1 electrón los aniones quedan con una carga de -1.

Puedes aprender mas sobre la regla del octeto aquí: https://brainly.com/question/18892451

Answer:

chromatography is based on the principle where molecules in mixture applied onto the surface or into the solid, and fluid stationary phase is separation from each other while moving with the aid of a mobile phase.

Can you join please.

It's urgent for help.

I believe that the answer to your question is letter D, normal line.

Additionally, according to the law of reflection, the angle of incidence is equivalent to the angle of reflection. This means that the angle of reflection is the angle between the normal line and the reflected ray.

I hope that this has helped you. Good day to you.

Answer:

3.60

Explanation:

Just use the log function on your calculator, the number you get transform it to positive

- log [tex](0.025x10^{-2}[/tex]) = 3.60

Answer: yes because it talks about what he pacifically he did and what the results was and he would probably need 2 get a little more data

Explanation:

Answer:

Protons= 11

neutrons= 12

electrons = 10

Explanantion:

Look for Na on periodic table

Atomic Number = 11

Atomic Mass = 23 (round it to be an integer)

Number of protons = Atomic number = 11

Number of neutrons = Atomic mass - atomic number = 23-11 =12

Number of electrons = 11 - e = ´+1 , electrons = 10

Answer:

Protons= 11

neutrons= 12

electrons = 10

Explanation:

That should be the answer :)

Answer:

Both particles A and B

Explanation:

A nucleus contains both protons and neutrons .

But protons are positively charged whereas neutrons have no charge.

[tex].[/tex]

Both particles A and B are most likely present inside the nucleus of the atom. Therefore, option (c) is correct.

The nucleus of an atom contains the particles protons and neutrons. Both the solid particles in an atom are responsible for 99.9% of the mass in the nucleus.

The protons are the positively charged particles that lie inside the nucleus. Therefore, the nucleus of an atom has a positive charge on it while the negatively charged electrons rotate around the nucleus.

The neutrons do not carry any charge. So we can say that the neutrons are neutral. Therefore, the charge on the nucleus is only due to protons.

The atomic powers which are holding the protons and the neutrons inside the nucleus are also vast. The protons are prsent very close to each other inside the tiny nucleus, so the electrostatic forces of repulsion act in the nucleus.

Therefore, particles with no charge and positive charge are most present in the nucleus of the atom.

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Answer:

You use a magnet and the fillings will go with the magnet.

Answer: Isotope-1: Hydrogen (H)

Isotope-2: Deuterium (H)

Explanation: The periodic table shows that the smallest element in hydrogen (H), at an average atomic weight of 1.008. Hydrogen-1 has one proton, one electron, and no neutrons, which adds to 1 AMU. Hyrogen-2 is an isotope of hydrogen that contains 1 neutron in addition to the proton, bringing the mass to 2 AMU. It is only at 0.0156% abundance on Earth and is given the name Deuterium, sometimes refered to as "heavy water" when incorporated into a water molecule. A third isotope has 2 neutrons, and is called Tritium.

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Hand tools in need of repair or replacement create hazards. Tools with wooden handles, like hammers and axes, can splinter or break in the middle of use, resulting in injury. Impact tools like chisels are unsafe for use if they have “mushroomed” heads because they could shatter on impact and cause injury.

The density of the piece of metal is 2.12g/mL

HOW TO CALCULATE DENSITY:

Density (g/mL) = mass (g) ÷ volume (mL)

Density = 23.5/11.1

Density = 2.12g/mL

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Answer:

The answer is a compound.

it is a compound as it contains different elements

Explanation:

Answer:

0.00012 g/ml

Explanation:

g are 100 x cg, and litres are 1000 x ml, so the number 12 needs to be divided by 100 x 1000 = 100,000 in order to get the correct result.

But you can also work through and figure it out logically.

1 cg = 0.01 g, so 12 cg = 0.12 g

So you have 0.12 g in 1 litre, which is 0.12 g in 1000 ml.

This means that in 1 ml you have 0.12/1000 = 0.00012 g.

The field of study that Christian Doppler's work influenced the most was about light waves.

Hope it helps you.

Answer:

that would be B

Explanation:

Answer:

Yes

Explanation:

Answer:

[tex]\boxed {\boxed {\sf 6.4 \ atm}}[/tex]

Explanation:

We are asked to find the pressure of a gas in a can given a change in temperature. We will use Gay-Lussac's Law, which states the pressure of a gas is directly proportional to the temperature. The formula for this law is:

[tex]\frac {P_1}{T_1}= \frac {P_2}{T_2}[/tex]

Initially, the gas in the aerosol can has a pressure of 3.10 atmospheres at a temperature of 25 degrees Celsius.

[tex]\frac { 3.10 \ atm}{25 \textdegree C}=\frac{P_2}{T_2}[/tex]

The temperature is increased to 52 degrees Celsius, but the pressure is unknown.

[tex]\frac { 3.10 \ atm}{25 \textdegree C}=\frac{P_2}{52 \textdegree C}[/tex]

We are solving for the new pressure, so we must isolate the variable [tex]P_2[/tex]. It is being divided by 52 degrees Celsius. The inverse operation of division is multiplication, so we multiply both sides of the equation by 52 °C.

[tex]52 \textdegree C *\frac { 3.10 \ atm}{25 \textdegree C}=\frac{P_2}{52 \textdegree C} * 52 \textdegree C[/tex]

[tex]52 \textdegree C *\frac { 3.10 \ atm}{25 \textdegree C}=P_2[/tex]

The units of degrees Celsius cancel.

[tex]52 *\frac { 3.10 \ atm}{25}=P_2[/tex]

[tex]52 *0.124 \ atm = P_2[/tex]

[tex]6.448 \ atm = P_2[/tex]

The original values of pressure and temperature have 2 and 3 significant figures. Our answer must be rounded to the least number of sig figs, which is 2. For the number we calculated, that is the tenths place. The 4 in the hundredth place tells us to leave the 4 in the tenths place.

[tex]6.4 \ atm \approx P_2[/tex]

The gas pressure in the can at 52 degrees Celsius is approximately 6.4 atmospheres.

Answer:

Regions of the Electromagnetic Spectrum

Wavelength (m)Frequency (Hz)Radio> 1 x 10-1< 3 x 109Microwave1 x 10-3 - 1 x 10-13 x 109 - 3 x 1011Infrared7 x 10-7 - 1 x 10-33 x 1011 - 4 x 1014Optical4 x 10-7 - 7 x 10-74 x 1014 - 7.5 x 1014

Answer:

cryolite

Explanation:

B B B B B

cryolite is the answer

Answer:

Matter:

toothpaste

gasoline

bacteria

cell

Not matter:

happiness

sound

Explanation:

Matter is something that has mass and volume. Happiness is just a feeling, it doesn't exist in 3d world. Sound is a wave or just the movement of matter (particles of matter). Others have masses and volumes.