A student wants to make a fair comparison of the reactivity of the metals with
hydrochloric acid.

Name two variables that must be kept constant.

Answer:

They also showed the effects of pressure on volume if temperature stayed the same

Explanation:

They also showed the effects of pressure on volume if temperature stayed the same is the experiment that will provide an evidence for Boyle's law.

Boyle's law states that "the volume of a fixed mass of a gas varies inversely as the pressure changes, if the temperature is constant".

Answer:

Density, [tex]d=2.09\ g/cm^3[/tex]

Explanation:

Given that,

Mass of a flask is 450 g

Volume of benzene added to the flask is 145 mL or 145 cm³

The weight of the flask and benzene is found to be 754 g.

We need to find the density of the benzene.

Weight of benzene added = total weight of flask and benzene-mass of flask

m = 754 g - 450 g

m = 304 g

Density = mass/volume

So,

[tex]d=\dfrac{304\ g}{145\ cm^3}\\\\d=2.09\ g/cm^3[/tex]

So, the density of the benzene is [tex]2.09\ g/cm^3[/tex].

Answer & Explanation:

Susana's red crystal sample is a compound because it was broken down into a gas and blue powder. It is not an element because elements cannot be broken down into simpler substances by ordinary means, such as heating.

Answer:

Susana's red crystal sample is a compound because it was broken down into a gas and blue powder. It is not an element because elements cannot be broken down into simpler substances by ordinary means, such as heating.

Explanation

Sample response form Edg

Answer: valence electrons are simply the electrons in the outer most ring of the chart. in your example, this atom has four valence electrons.

Answer:

The Answer is ________ Please Make sure You Put it In and Trust Have a wonderful day/Night:)

Explanation:

Answer:

3 is B 4 is the number 3

Explanation:

I hope this helps :D

Answer:

Lose energy

Explanation:

The molecules are moving from a liquid (molecules slide past one another) to a solid (molecules barely move) so are losing energy

Answer:

C

Explanation:

The geographical features acted as a natural defense for Egypt against enemies from the south is cataracts of Nile. Hence, option C is correct.

The Nile River, one of Egypt's most notable natural features, was the envy of neighboring civilizations and allowed the Egyptians maintain contact with populations in the Mediterranean region.

Huge deserts extend well beyond the lush terrain that surrounds the Nile River on both sides. The Sahara Desert, the world's biggest desert, is to the west. More desert and the Red Sea may be found east of the Nile. These deserts served as an excellent natural defense against invaders.

The Egyptians had built-in fortifications thanks to the river and the desert. The delta of the Nile River is swampy. Egypt was unable to construct a port at the mouth of the Nile as a result. Invaders found it hard to approach Egyptian villages along the river as a result.

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Answer:

2. 232 & 86

Explanation:

Answer:

Initial Speed ____4m/s. Final Speed ______6m/s. Time ______5 seconds . Acceleration =________0.4m/s²

Explanation:

The acceleration is the rate of change of velocity during time t .

acceleration = Final velocity- Initial velocity/ Time

                    = Vf- Vi/ t

            a = Δv/ Δt

                   = 6m/s- 4m/s/ 5s

                   = 2m/s/ 5s

                  = 0.4m/s²

It can also be defined as the difference of the initial and final velocity ( velocities measured in meters per second) during the given time t measured in seconds .The SI unit of acceleration is meter per second squared.

If the velocities are not measured in meters per second or time is not measured in seconds then the units are changed accordingly.

Answer:

I believe C

Explanation:

Saying it always does one thing or another is mostly not the case. When it comes to biodiversity, there can be positive impacts! But an ecosystem is affected by everything in it's biodiversity.

Answer:

there are many valleys and mountain in this region

magar,gurung,brahmins are the main inhabitants of this province

there is possibility of tourism development in this province

production of apple in mountains and coffe in hilly has made this region popular .

Hope it helps

Answer:

There are many valleys and mountain in this region . Magar, Gurung, and Brahmins are the main inhabitants of this province . There is possibility of tourism development in this province . Production of apple in mountains and coffee in hilly has made this region popular.

Explanation:

May I have brainliest please? :)

Answer:

Covalent Bonds

General Formulas and Concepts:

Explanation:

We have 3 types of bonds: Polar Covalent, Nonpolar Covalent, and Ionic bonds.

Nonpolar Covalent bonds share the electrons equally between the compound.

Polar Covalent bonds do NOT share the electrons equally, but STILL SHARE the electrons; the electron tends to stay with the element with the stronger electron affinity and thus creates dipoles.

Ionic bonds DO NOT share electrons. The electrons are transferred to the respective elements.

Answer:

4) how charged the object creating the field is and the distance between the two charged objects

Answer:

This question is incomplete

Explanation:

This question is incomplete because of the absence of options. However, Rutherford's model of an atom highlighted the following (which you can use to determine your answer from the missing options)

1) electrons move in fixed circular part (now referred to as electron shells) around a central positively charged nucleus

2) The size of the nucleus is very small relative to the size of the atom

Answer:

Here is what I got from reading this question...

Explanation:

So if you dissolve 7.5625- g of CaCl2 in water, dissolve well and then add distilled in a 250- ml standard flask upto the mark and shake well for uniform Concentration, you will get 0.25- M CaCl2 solution.

Answer:

wind can carry sand and dirt in the air. if the sand or dirt hit a material repeatedly, the material can break down after being hit multiple times. with this, materials can erode.

Explanation:

Answer:

increase is the answer for both ig?

Explanation:

Given elements:

  F, Sr, P, Ca, O, Br, Rb, Sb, Li, S

Elements with the same chemical reactivity will belong to the same group on the periodic table. This implies that elements in the same column will have the same reactivity;

  Li and Rb are both alkali metals in group 1

  Ca and Sr are both alkali earth metals in group 2

  F and Br are halogens in group 7

  O and S are group 6 elements

 P and Sb are both in group 5 on the periodic table

So these groupings show elements with the same chemical properties.

The following elements can be put into five pairs of elements that have similar chemical reactivity in the following ways: F and Br, Sr and Ca, P and Sb, O and S, Li and Rb.

The periodic table shows and displays the tabular arrangement of atomic elements as they are categorized into groups and periods. Elements in the same groups exhibit certain chemical properties and reactivity with one another.

On the periodic table;

Therefore, we can conclude that we've fully understood the concept of how chemical reactivity works with elements that are grouped in the same group.

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Answer:

Be careful about when to use capital letters. For example, CO means a molecule of carbon monoxide but Co is the symbol for cobalt

Explanation:

The total amount of heat : 225.704 kJ

Heat of vaporization(ΔH vap) : heat needed to vaporize 1 mole of water , units : kJ/mol

For water at boiling point (100 °C) : ΔH vap = 40.66 kj/mol

mole of 100 g water :

[tex]\tt \dfrac{100}{18.015}=5.551[/tex]

so total Heat :

[tex]\tt 40.66\times 5.551=225.704~kJ[/tex]

Answer:

Carbon has a valency of+4 and chlorine has a valency equal to −1.Compound is Carbon tetrachloride CCl4.

Answer:

Trigonal planar

Explanation:

The geometry will be trigonal planar because B has 3 valence electron and all three each of it will form single bond with with electron of chlorine

The given compounds is boron trichloride BCl₃. The geometry of this molecule is trigonal planar. Thus option B is correct.

Boron trichloride BCl₃ is a covalent compound formed by boron and three chlorine atoms.Boron is 5th element in periodic table and chlorine is 17th element.

Here, boron have 3 valence electron and Cl have 7 electrons in its valence shell. Boron shares its three valence electrons each to each chlorine. Industrially it is prepared by chlorinating carbon and boron oxide at higher temperature.

Trihalides of boron have a trigonal planar geometry because, each chlorine bond makes an angle of 120° with the boron atom. Thus it assumes the shape of a triangle with three chlorines in three corners.

Hence, the compound boron trichloride, BCl₃ have a geometry of trigonal planar and thus option B is correct.

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Answer:

4.5moles

Explanation:

Given parameters:

Mass of Na₃P = ?

Unknown:

Number of moles  = ?

Solution;

The number of moles in a given substance can be derived from the expression below;

    Number of moles = [tex]\frac{mass}{molar mass}[/tex]  

Molar mass of  Na₃P   = 3(23) + 31 = 100g/mol

   Number of moles  = [tex]\frac{450}{100}[/tex]   = 4.5moles

Answer:

3 x 10^9

Explanation:

Answer:

Na the valency electrons is 1

The ion charge is positive 1

K the valency electrons is 1

The ion charge is positive 1

Explanation:

Mg the valency electron is 2 The ion charge is positive 2

Ca the valency electron is 2 The ion charge is positive 2

Al the valency electron is 3 The ion charge is positive 3

O the valency electron is 2 The ion charge

is negative 2

F the valency electron is 1 The ion charge is negative 1

Cl the valency electron is 1 The ion charge

is negative 1

N the valency electron is 3 The ion charge is negative 3

S the valency electron is 2 The ion charge is

negative 2

Na the valency electrons is 1, The ion charge is positive 1 and K the valency electrons is 1, The ion charge is positive 1.

Mg the valency electron is 2 The ion charge is positive 2, Ca the valency electron is 2 The ion charge is positive 2 and Al the valency electron is 3 The ion charge is positive 3.

O the valency electron is 2 The ion charge, is negative 2 and F the valency electron is 1 The ion charge is negative 1, Cl the valency electron is 1 The ion charge is negative 1

N the valency electron is 3 The ion charge is negative 3, S the valency electron is 2 The ion charge is negative 2.

Therefore, Na the valency electrons is 1, The ion charge is positive 1 and K the valency electrons is 1, The ion charge is positive 1.

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Answer:

It is where the water lies underground