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Blababa [14]
3 years ago
6

Which of the following is true about extinction? A. Only one extinction has occurred during the Earth's history. B. Plant specie

s can become extinct, but animal species cannot. C. Extinctions have occurred many times throughout the Earth's history. D. Animal species can become extinct, but plant species cannot.
Chemistry
2 answers:
ycow [4]3 years ago
8 0

Answer:

C. Extinctions have occurred many times throughout the Earth's history.

Explanation:

lozanna [386]3 years ago
6 0






C.exstinctions have occurred many times
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Is cooking raw tomatoes a physical or a chemical change?<br>Explain why?
salantis [7]

When you are asked a question like this, you can always ask yourself this question. Can I change it back after this change? For example, if you are burning wood, you cannot bring it back to wood after you burn it, therefore, it is a chemical change. However, if you boil and evaporate water, you can make the water condense again back into its liquid form. In this case, you cannot bring the tomato back to its raw state. Therefore, cooking raw tomatoes is a chemical change.

7 0
3 years ago
11
Bess [88]

Answer:

Explanation:

<u>Manganese (VII) ion (an anion) has the formula MnO₄⁻</u>. A polyatomic ion is an ion that is made up of more than one atom. For example, MnO₄⁻ and NH₄⁺. Since the ion provided in the question is an anion, the polyatomic ion that would react with it will have to be a cation (positively charged).

<u>The polyatomic cation that will react with MnO₄⁻ to form a neutral compound is NH₄⁺ (ammonium ion) to form NH₄MnO₄ (Ammonium permanganate).</u>

6 0
3 years ago
An analysis of a sugar compound is found to contain 132 grams of carbon (C), 22 grams of hydrogen (H), and 176 grams of oxygen (
ddd [48]
132 g of C  ,   22 g of H   , 176 g of O

132 + 22 + 176 => 330 g <span>of the substance

</span>Now convert the masses in <span>moles :
</span>
C = 12.0 u        H = 1.0 u       O = 16.0 u

C = 132 / 12.0 => 11 moles

H = 22 / 1.0 => 22 moles

O = 176 / 16.0 => 11 moles

Using the values obtained the lowest proportion in mols of elements present, simply divide the values found for the least of them<span>:
</span>
C = 11 / 11 => 1

H = 22 / 11 => 2

O = 11 / 11 => 1

 formula empirically <span>is : CH</span>₂O

hope this helps!


8 0
3 years ago
State general trend for metal properties as you go left to right across a period
qwelly [4]

Periodic trends are specific patterns that are present in the periodic table that illustrate different aspects of a certain element, including its size and its electronic properties. Major periodic trends include: electronegativity, ionization energy, electron affinity, atomic radius, melting point, and metallic character. Periodic trends, arising from the arrangement of the periodic table, provide chemists with an invaluable tool to quickly predict an element's properties. These trends exist because of the similar atomic structure of the elements within their respective group families or periods, and because of the periodic nature of the elements.

Electronegativity Trends

Electronegativity can be understood as a chemical property describing an atom's ability to attract and bind with electrons. Because electronegativity is a qualitative property, there is no standardized method for calculating electronegativity. However, the most common scale for quantifying electronegativity is the Pauling scale (Table A2), named after the chemist Linus Pauling. The numbers assigned by the Pauling scale are dimensionless due to the qualitative nature of electronegativity. Electronegativity values for each element can be found on certain periodic tables. An example is provided below.


From left to right across a period of elements, electronegativity increases. If the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one. Conversely, if the valence shell is more than half full, it is easier to pull an electron into the valence shell than to donate one.

From top to bottom down a group, electronegativity decreases. This is because atomic number increases down a group, and thus there is an increased distance between the valence electrons and nucleus, or a greater atomic radius.

Important exceptions of the above rules include the noble gases, lanthanides, and actinides. The noble gases possess a complete valence shell and do not usually attract electrons. The lanthanides and actinides possess more complicated chemistry that does not generally follow any trends. Therefore, noble gases, lanthanides, and actinides do not have electronegativity values.

As for the transition metals, although they have electronegativity values, there is little variance among them across the period and up and down a group. This is because their metallic properties affect their ability to attract electrons as easily as the other elements.

According to these two general trends, the most electronegative element is fluorine, with 3.98 Pauling units.



6 0
3 years ago
The reaction 2 ClO2(g) + F2(g) → 2 FClO2(g) is first-order in both ClO2 and F2. When the initial concentrations of ClO2 and F2 a
kupik [55]

Answer:

3. 75.0%

Explanation:

2 ClO2(g) + F2(g) → 2 FClO2(g)

First order with respect to ClO2 and F2.

This means the rate equation is given as;

Rate = k [ClO2][F2]

When the initial concentrations of ClO2 and F2 are equal?

Let's assume an initial value of 1 for both reactants, so rate equation is given as;

Rate = k * 1 * 1 = k

The rate after 25% of the F2 has reacted is what percent of the initial rate?

The concentration left of F2 is 75% ( 100% - 25%) = 0.75

Concentration of ClO2 remains 1.

So rate equation is given as;

Rate = k * 1 * 0.75 = 0.75 k

Comparing 0.75k and k.

This means our answer is;

3. 75.0%

6 0
3 years ago
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