Which microscope came out first

2. Perform this operation and report the answer to the correct number of significant figures: What is the mass of a cube of alum

lyudmila [28]

2) D = m/V. Knowns: V = (4 x 4 x 4) = (64) D = 2.7

2.7 = m/(64)

172.8 = m or with significant figures, 170

3) Knowing the model of the atom is crucial becuase without understanding what everything is made up of, then there is no way of telling how it is going to react with outside things. Knowing the model of the atom can better help us visualize what it looks like and it can also tell us how it is going to react baced on its propertys and what it is made of.

4) Dalton's theory tells us that 1, all matter is made of atoms, which are indivisible and indestructiable. This does not agree with todays findings because we know that atoms can be broken up into sub atomic particals, and even those sub atomic particals can be broken down even further to sub-sub-atomic particals such as quarks and borons. 2, We also know about Isotopes. Isotopes are the same atom but with different atomic weights becaus of the amount of nutrons in the nuclei.

5) If an element has 12 protons and 17 neutron, in order to be stable and found in nature, the atom must have 12 protons because protons are positive and neutrons have a charge of 0 so in order to balence the atom out, the electrons, with a negitive charge, must be the same number as the protons.

7 0

3 years ago

Calculate how many grams of iron can be made from 16.5 grams of iron(III) oxide if hydrogen gas is in excess?

miss Akunina [59]

Taking into account the reaction stoichiometry, 11.54 grams of Fe are formed from 16.5 grams of iron(III) oxide if hydrogen gas is in excess.

<h3>Reaction stoichiometry</h3>

In first place, the balanced reaction is:

Fe₂O₃ + 3 H₂ → 2 Fe + 3 H₂O

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Fe₂O₃: 1 mole
H₂: 3 moles
Fe: 2 moles
H₂O: 3 moles

The molar mass of the compounds is:

Fe₂O₃: 159.7 g/mole
H₂: 2 g/mole
Fe: 55.85 g/mole
H₂O: 18 g/mole

Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

Fe₂O₃: 1 mole ×159.7 g/mole= 159.7 grams
H₂: 3 moles ×2 g/mole= 6 grams
Fe: 2 moles ×55.85 g/mole= 111.7 grams
H₂O: 3 moles ×18 g/mole= 54 grams

<h3>Mass of each product formed</h3>

The following rule of three can be applied: if by reaction stoichiometry 159.7 grams of Fe₂O₃ form 111.7 grams of Fe, 16.5 grams of Fe₂O₃ form how much mass of Fe?

$mass of Fe=\frac{16.5 grams of Fe_{2} O_{3} x111.7 grams of Fe}{159.7 grams of Fe_{2} O_{3}}$

<u><em>mass of Fe= 11.54 grams</em></u>

Then, 11.54 grams of Fe are formed from 16.5 grams of iron(III) oxide if hydrogen gas is in excess.

Learn more about the reaction stoichiometry:

brainly.com/question/24741074

brainly.com/question/24653699

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7 0

2 years ago

How would you test to find out if<br> indigestion tablets are better than using<br> baking powder?

Orlov [11]

Go here and see how:
http://www.rsc.org/learn-chemistry/resource/res00000698/using-indigestion-tablets-to-neutralise-an-acid?cmpid=CMP00005978

7 0

4 years ago

Explain why groups 14 and 15 are better representatives of mixed groups than groups 13 and 16

Brrunno [24]

<h3><u>Answer</u>;</h3>

Groups 14 and 15 each contain metals, nonmetals, and metalloids while Group 13 contains metals and a metalloid, and Group 16 contains metalloids and nonmetals.

<h3><u>Explanation;</u></h3>

Groups 13–16 of the periodic table contain one or more metalloids, in addition to metals, nonmetals, or both.
Unlike other groups of the periodic table, which contain elements in one class, groups 13–16 referred to as mixed groups contain elements in at least two different classes. In addition to metalloids, they also contain metals, nonmetals, or both.
<em><u>Group 14 also known as the carbon group contains carbon which is a non metal, silicon and germanium which are metalloids and tin and lead which are metals.</u></em>
<em><u>Group 15 also known as the Nitrogen group contains non metals such as oxygen, metalloid tellurium and a metal polonium.</u></em>

3 0

4 years ago

A physical change occur when a

Viefleur [7K]

The answer is C. Glue gun melts a glue stick.

5 0

4 years ago

Read 2 more answers