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kotykmax [81]
3 years ago
9

When was the "Permian Era"?

Chemistry
2 answers:
timurjin [86]3 years ago
6 0
The Permian period lasted from 299 to 251 million years ago and was the last period of the Paleozoic Era.
klemol [59]3 years ago
4 0

Answer:

298.9 million years ago - 251.902  million years ago

Explanation:

It might be in the 2011 Earth Science Review Packet so maybe go check that out

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How many grams are in 2.3 x 1024 formula units of KNO3?
Harlamova29_29 [7]
<h2>Answer:</h2>

390 g KNO₃

<h2>General Formulas and Concepts:</h2><h3><u>Chemistry</u></h3>

<u>Atomic Structure</u>

  • Reading a Periodic Table
  • Using Dimensional Analysis
  • Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.
<h3><u>Math</u></h3>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right
<h2>Explanation:</h2>

<u>Step 1: Define</u>

2.3 × 10²⁴ formula units KNO₃

<u>Step 2: Identify Conversions</u>

Avogadro's Number

Molar Mass of K - 39.10 g/mol

Molar Mass of N - 14.01 g/mol

Molar Mass of O - 16.00 g.mol

Molar Mass of KNO₃ - 39.10 + 14.01 + 3(16.00) = 101.11 g/mol

<u>Step 3: Convert</u>

<u />2.3 \cdot 10^{24} \ formula \ units \ KNO_3(\frac{1 \ mol \ KNO_3}{6.022 \cdot 10^{23} \ formula \ units \ KNO_3} )(\frac{101.11 \ g \ KNO_3}{1 \ mol \ KNO_3} ) = 386.172 g KNO₃

<u>Step 4: Check</u>

<em>We are given 2 sig figs. Follow sig fig rules and round.</em>

386.172 g KNO₃ ≈ 390 g KNO₃

5 0
3 years ago
Radium has a half-life of 1,620 years. In how many years will a 1 kg sample of radium decay and reduce to 0.125 kg of radium?
Tasya [4]
We can calculate years by using the half-life equation. It is expressed as:

A = Ao e^-kt

<span>where A is the amount left at t years, Ao is the initial concentration, and k is a constant.

</span>From the half-life data, we can calculate for k.

1/2(Ao) = Ao e^-k(1620)
<span>k = 4.28 x 10^-4
</span>
0.125 = 1 e^-<span>4.28 x 10^-4 (</span>t)
t = 4259 years
7 0
3 years ago
Read 2 more answers
PLEASE HELP I got this wrong on an exam but got it wrong and i don’t know why!
lord [1]

Answer:

D.5,55cm+/-0,005cm

Explanation:

so this is the answer

5 0
3 years ago
Which biome contains mostly coniferous trees and receives 35 to 100 cm of rain per year? deciduous forest taiga (boreal forest)
Sever21 [200]

option B, taiga (boreal forest).

(hope this helps ^^)

8 0
3 years ago
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A phase diagram assumes ______ is kept constant. temperature volume pressure density
algol [13]

pressure......................................

6 0
3 years ago
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