Newton's first law of motion says that an object in motion will remain in

Which rocky planet is the most similar to earth.Why?

Alchen [17]

Answer:

Mars

Explanation:

Mars is the planet with features that are really similar to the earth. As a matter of fact, Mars and the earth are referred to as "twin planets".

Mars and Earth are believed to have historically had even more similar attributes, however, that of mars was lost due to changes in the solar system.

The two planets are mostly similar because of their relatively similar size and proximity to the sun.

5 0

3 years ago

How many grams of Na2s do we need to dissolve in 200ml of water to get a solution that is 0.2 M?

DochEvi [55]

We know that the molarity of a solution is calculated by the following equation:

$Molarity = \frac{# moles}{L}$

That being said we are given two of the 3 things that we need: Volume of water, as well as the molarity of the solution. Let's plug those in to the equation to find how many moles of $Na_{2}S$ that we need:

$0.2 M = \frac{moles}{0.2 L}$ => $moles =0.04$

This means that we have 0.04 moles of $Na_{2}S$ .

In order to calculate the number of grams that we need for this solution, we must first calculate how many grams of $Na_{2}S$ are in 1 mole. We do this by taking the atomic masses of each element from the periodic table and adding them together.

Na = 22.99 g
S = 32.06 g

We have 2 Na's, and we have 1 S. So lets add them together:

2(22.99) + (32.06) = $\frac{78.04g}{mol}$ .

Since we need 0.04 moles of $Na_{2}S$ , we can multiply the molar weight of the molecule times the amount of moles needed to find the total grams that we need for the solution:

$\frac{78.04g}{mol}*0.04 moles = 3.1216 g$

Now we know that in order to make a 0.2 M solution of $Na_{2}S$ , we must use 3.1216 grams.

4 0

4 years ago

2HCI + Na, so, - 2NaCl + H,so,

Tems11 [23]

Answer:

None of the options are correct.

The correct answer is 1.10g

Explanation:

First, we'll begin by balancing the equation given above. This is illustrated below:

2HCl + 2Na —> 2NaCl + H2

Next, let us calculate the mass of HCl that reacted and the mass of H2 produced from the balanced equation. This is illustrated below:

Molar Mass of HCl = 1 + 35.5 = 36.5g/mol

Mass of HCl from the balanced equation = 2 x 36.5 = 73g

Molar Mass of H2 = 2x1 = 2g/mol

Now we can easily find the mass of H2 produced when 40g of HCl reacted as shown below:

From the balanced equation,

73g of HCl produced 2g of H2.

Therefore, 40g of HCl will produce = (40 x 2)/73 = 1.10g of H2.

From the calculations made above,

40g of HCl produced 1.10g of H2

8 0

3 years ago

Chlorine can be prepared in the laboratory by the reaction of manganese dioxide with hydrochloric acid, HCl ( aq ) , as describe

Nataly [62]

Answer:

0.9483 grams of manganese dioxide should be added to excess HCl.

Explanation:

Pressure of the chlorine gas = P = 795 Torr = 1.046 atm (1 atm = 760 Torr)

Volume of the chlorine gas = V = 255 ml = 0.255 L

Temperature of the chlorine gas = T = 25°C= 298.15 K

Moles of chlorine gas = n

Using ideal gas equation:

PV = nRT

$n=\frac{PV}{RT}=\frac{1.046 atm\times 0.255 L}{0.0821 atm l/mol k\times 298.15 K}$

n = 0.01090 mol

$MnO_2 ( s ) + 4 HCl ( aq)\rioghtarrow MnCl_2 ( aq ) + 2 H_2O ( l ) + Cl_2 ( g )$

According to reaction , 1 mole of chlorine gas is obtained from 1 mole of manganese dioxide.

Then 0.01090 moles of chlorine gas will be obtained from:

$\frac{1}{1}\times 0.01090 mol=0.01090 mol$ manganese dioxide

Mass of 0.01090 moles of manganese dioxide:

0.01090 mol × 87 g/mol = 0.9483 g

8 0

3 years ago

3.Write the symbol of the element that has a charge of +1 when it has 71 electrons.

tigry1 [53]

The symbol : $\tt _{72}^{178}Hf^{+1}$

<h3>Further explanation </h3>

There are two components that accompany an element, the mass number and atomic number

Atoms are composed of 3 types of basic particles (subatomic particles): <em>protons, electrons, and neutrons </em>

The Atomic Number (Z) indicates the number of protons and electrons in an atom of an element.

Atomic number = number of protons = number of electrons ⇒ neutral number

Atomic mass is the sum of protons and neutrons

Atomic Number (Z) = Atomic mass (A) - Number of Neutrons

The element has 71 electrons and a charge of +1 , so

Number of protons = 71 + 1 = 72

Number of protons = the atomic number = 72

The element with atomic number 72 is Hafnium(Hf)

The atomic mass of Hf = 178 g/mol

4 0

3 years ago