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Lyrx [107]
3 years ago
11

Which is the best example of a pure substance? a) peanuts b) milk c) gold d) air?

Biology
2 answers:
Evgen [1.6K]3 years ago
8 0
B) peanuts.....I think
anzhelika [568]3 years ago
5 0

gold. they are clean.


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Iron-55 has a half-life of 3 years. How much of a 40 gram sample will remain after 12 years? A. 0 grams B. 4 grams C. 2.5 grams
Readme [11.4K]

Answer:

\boxed {\boxed {\sf C. \ 2.5 \ grams }}

Explanation:

We are asked to find how much of a 40 gram sample remains after 12 years.

Iron-55 has a half-life of 3 years. Therefore, after 12 years, 4 half-lives have been completed.

  • 12 years/3 years = 4 half-lives

Every time a half-life is completed, half of the sample's mass decays. Remember we start with a 40 gram sample.

  • 1 half- life: 40 g / 2 = 20 g
  • 2 half-lives: 20 g / 2= 10 g
  • 3 half-lives: 10 g / 2 = 5 g
  • 4 half-lives: 5 g / 2 = 2.5 g

There is also a formula that can be used to solve this problem.

A= A_o(\frac {1}{2})^{\frac{t}{hl}

Where A₀ is the initial amount, t is the time, and hl is the half-life.

We know 40 grams is the inital amount, 12 years is the time, and 3 years is the halflife.

  • A₀= 40 g
  • t= 12
  • hl= 3

A= 40 \ g (\frac{1}{2})^\frac{12}{3}

A= 40 \ g (\frac{1}{2})^4

A= 40 \ g * 0.0625

\bold {A= 2.5 \ g}

After 12 years, <u>2.5 grams </u> of Iron-55 will remain.

4 0
2 years ago
The root of a flowering plant absorbs water and mineral ions mainly through:__________A. the epidermisB. the root hairsC. the ph
fgiga [73]

B ) root hair cells I guess so.....

4 0
3 years ago
What description best explains why viruses can become more pathogenic to host that were not affected by the virus before?
ANEK [815]

Answer:

New cells are naive to the infectious cells who attack it or they are not well prepared to deal with the different scenarios. But, the cells who are attacked before has the set or sequence of the viral or bacterial genome strand been identified by them, which leads to more safety or protection from these foreign bodies.

Explanation:

  • Mechanism To attack a host cell:

The viruses and other infectious material enters and attacks the host cell, by breaching its membrane wall and installing or leaving a gene of its own inside the cell. Which then combines with the genome of the cell and it goes through the process of replication, translation etc,along with the host cell machinery. Which then spreads the specific gene strand more in the environment

  • <u>Camouflage obtained by the infectious cell to hide it self:</u>

After the genome enters the host cell at first it does not recognizes the strands or foreign cells, as they cover there body with a camouflage sort of membrane and they look more like the body cells.

  • <u>Reactions by the host cell and as a whole the body:</u>

The organisms detects the genome of the infections cells or strand, as they store the data about it in its server or database. As if the next time they were under attack then precautions will be there by the host cell to deal with it.

As for the cell who are never attacked before will be less safe to deal with these foreign bodies.

5 0
3 years ago
What is a simple definition of the noun "complex" in Biology?
dolphi86 [110]

Answer:

complexity. (uncountable) The state of being complex; intricacy; entanglement. (countable) That which is and renders complex; intricacy; complication.

Explanation:

hope it helps!!

4 0
3 years ago
Read 2 more answers
What are the 3 types of symbiosis?
Slav-nsk [51]
And if and because or up down and below or above or beneath
8 0
3 years ago
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