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Zepler [3.9K]
3 years ago
11

1. (10 pt) How are elements arranged in the Periodic Table? A. by their properties B. alphabetically C. by how much they are wor

th D. in the order they were discovered 2. (10 pt) Which is the correct symbol for the element silicon? A. SI B. S C. Si D. Sil 3. (10 pt) All atoms of an element are ________ . A. flammable B. visible under a microscope C. alike D. different 4. (10 pt) Elements that are usually shiny and good conductors of heat and electricity are known as ________________. A. gases B. metals C. solids D. nonmetals 5. (10 pt) The most recent model of an atom is the _______________. A. Bohr model B. Einstein model C. Nucleus model D. Electron Cloud model 6. (10 pt) Elements that are usually dull, brittle, and do not conduct electricity are known as A. gases B. metals C. solids D. nonmetals 7. (10 pt) Elements join together to form A. compounds B. ions C. protons D. atomic masses 8. (10 pt) Which picture best shows an atom? A. B. C. D. 9. (10 pt) In order for a chemical reaction to take place, a certain amount of _______________ must be present. A. heat B. friction C. chemicals D. energy 10. (10 pt) Enzymes are ____________ in the body that speed up chemical reactions. A. catalysts B. cells C. concentrations D. chloroplasts
Chemistry
1 answer:
Vladimir79 [104]3 years ago
4 0
1. Elements are ordered by their properties.
2. The symbol is Si. Elemental symbols have no more than 2 letters(except for unidentified elements), and only the first letter is capitalized.
3. All atoms of an element are alike.
4. Metals are shiny and can conduct. They are found on the left side of the periodic table.
5. The most recent model is the Electron Cloud model, or the Schrödinger model.
6. Nonmetals are dull and don’t conduct.
7. MULTIPLE elements conjoin to form compounds. If all the atoms are the same, it’s still an element.
8. I can’t see the picture, sorry.
9. In order for a reaction to take place, energy must be present. This can be in the form of heat, though, but it’s not universal.
10. Enzymes are catalysts that speed up chemical reactions.
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Write the chemical equation: <br> hydrogen peroxide decomposes to yield oxygen gas and water.
Doss [256]

Explanation:

2 H2O 2 → 2H 2 O + O2.........

6 0
3 years ago
A 12 gram piece of Cu at 475 oC is placed in contact with a 15 gram piece of Cr at 265 oC.
ale4655 [162]

Answer:

349.22°C

Explanation:

Let the final temperature of the two pieces of metal be x.

Now, the warmer metal which is C u reduces from 475°C to x. Thus Δt for C u is; Δt1 = 475 - x.

The cooler metal Cr increases in temperature from 265°C to x. Thus, it's change in temperature is Δt for Cr is; Δt2 = x - 265.

Now from conservation of energy, the amount of energy leaving the C u metal is equal to the amount of energy entering the Cr metal.

Thus;

q_lost = q_gain

Where;

q_lost = m1•c1•Δt1

q_gained = m2•c2•Δt2

Now, c1 & c2 are the specific heat capacity of C u and Cr respectively.

From online tables, c1 = 0.385 J/g°C and c2 = 0.46 J/g°C

We are given;

m1 = 12g and m2 = 15g

Thus;

12 × 0.385 × (475 - x) = 15 × 0.46 × (x - 265)

2194.5 - 4.62x = 6.9x - 1828.5

6.9x + 4.62x = 2194.5 + 1828.5

11.52x = 4023

x = 4023/11.52

x = 349.22°C

4 0
3 years ago
A postulate of the kinetic molecular theory is listed.
valina [46]

Answer:

Postulate: Gas particles are extremely small and are far apart.

The activities can be used to demonstrate the postulate is :

<u>Observing colored gas spreading into an inverted jar placed on top of a jar containing the gas</u>

<u />

Explanation:

colored gas spreading into an inverted jar placed on top of a jar containing the gas:

This occur because of two reasons:

1. <em><u>The Gaseous particles are largely spaced . There is large distance between the gases molecule</u></em>

<em><u>2. The gases are in continuous motion . Hence they posses very high kinetic energy . This is the reason they mixes quickly if placed in a jar.</u></em>

<em><u>This occur by the process of diffusion. </u></em>

Diffusion of Gases: The intermixing of particles from the region of high concentration to low concentration.

The coloured gas goes into the space between the gaseous molecule present in the jar.(Gases are far apart)

As soon as the coloured gas is mixed in the jar , It spread quickly by diffusion because , The gaseous particles are extremely small and are far apart.

5 0
3 years ago
How many moles of H2 are produced from 5.8 moles of NH3
vodomira [7]

Answer:

1. 8.7moles of H2

2. 2.25moles of O2

Explanation:

1. 2NH3 —> N2 + 3H2

From the equation,

2moles of NH3 produce 3 moles of H2.

Therefore, 5.8moles of NH3 will produce Xmol of H2 i.e

Xmol of H2 = (5.8x3)/2 = 8.7moles

2. C3H8 + 5O2 —> 3CO2 + 4H2O

From the equation,

5moles of O2 produced 4moles of H2O.

Therefore, Xmol of O2 will produce 1.8mol of H2O i.e

Xmol of O2 = (5x1.8)/4 = 2.25moles

4 0
3 years ago
How are the properties of water affected by hydrgen bonding?
olasank [31]
The hydrogen bonds that form between water molecules account for some of the essential and unique properties of water. The attraction created by hydrogen bonds keepswater liquid over a wider range of temperature than is found for any other molecule its size.

Hope this helped!
4 0
3 years ago
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