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Rainbow [258]
3 years ago
8

Give two reasons why the flame test is sometimes invalid

Chemistry
2 answers:
Harlamova29_29 [7]3 years ago
7 0

Answer: 1.A false positive and 2.A false negative.

Explanation:

A false positive the classic example is the contamination of almost any sample with sodium ions which gives an intense yellow line even when the sodium is present as only impurity.

A false negative here sodium ions is the culprit that masks other emissions unless the emissions are resolved spectroscopically rather than simply visually.

zlopas [31]3 years ago
6 0
The two reason behind the invalidity of flame test are false positive and false negative.
while performing the flame test you must have to be accurate otherwise you will get false results may be positive for some element or may be negative in case the element is present. The main reason to get the false positive and false negative is the presence and contamination of sodium.
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Rus_ich [418]
<span>1. A scientific hypothesis can become a theory if the hypothesis is tested extensively and competing hypothesis are eliminated. A scientific hypothesis is a proposed explanation made on the basis of reasoning without any assumption. For hypothesis to be termed a scientific hypothesis, it has to be something that can be supported or refuted through carefully crafted experimentation or observation.

  2. A preliminary untested explanation that tries to explain how or why thing happen in the manner observed is a scientific hypothesis. A primary trait of a hypothesis is that something can be tested and that those tests can be replicated. A hypothesis is often examined by multiples scientists to ensure the integrity and veracity of the experiment. The process can take years, and in many cases hypothesis do not go any further in the scientific method as it is difficult to gather sufficient supporting evidence. </span>
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4 years ago
Wetlands help to prevent flooding. Please select the best answer from the choices provided T F
balu736 [363]
True, wetlands help to prevent flooding.
8 0
3 years ago
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Round the following number to four significant figures and express the result in standard exponential notation: 442,722 *
OleMash [197]

Answer:

4.427 × 10⁵

Explanation:

In mathematics, rounding up a number is a way to get a more simpler figure but not too distant from the original number. Rounding up a whole number like this (442722) to significant figures means having only four non-zero digits in the figure i.e. 442722 ~ 442700.

This means that 442722 has been rounded up to 4s.f. Hence, to use scientific notations to represent our answer, we count the number of decimal places from right to left i.e.

442700 = 5 decimal places if the point is between 4 and 4 i.e. 4.427

Therefore, the figure 442700 can be written as 4.427 × 10⁵ using scientific notation.

5 0
3 years ago
The density of lead is 11.3 g/cm. What is the mass of a cube of lead with 10.0 cm on each edge? Show work please.​
tresset_1 [31]

Mass of the lead cube :

  • \boxed{ \boxed{11.3 \:  \: kg}}

4 0
3 years ago
A piece of copper has a volume 130 L. What is the mass of the sample, in units of kilograms?
Reil [10]

Answer: The mass of the sample is 1264.800 kg.

Explanation:

Mass of the piece of copper = m

Volume of the copper price = 130 L=130,000 cm^3

1 L= 1,000 cm^3

Density=8.96 g/cm^3=\frac{Mass}{Volume}=\frac{Mass}{130,000 cm^3}

m=Density\times Volume=8.96 g/cm^3\times 130,000=1,264,800 g

m = 1,264,800 g = 1,264.800 kg (1 kg = 1000 g)

The mass of the sample is 1264.800 kg.

3 0
3 years ago
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