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bagirrra123 [75]
2 years ago
8

Which of the following is not an alkali?

Chemistry
1 answer:
Troyanec [42]2 years ago
7 0

Answer:

Đồng oxit

Explanation:

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24.3 2 An artifact classified as seeds, found in a site at Newlands Cross, Ireland, is found to have a 14C radioactivity of 0.10
Rina8888 [55]

Answer:

Age ≅ 7500 years

Explanation:

All radioactive decay is 1st order kinetics and described by the expression

A = A₀e^-kt => t = ln(A/A₀) / -k

k = 0.693 / t(half life) = (0.693 / 5730)yrs⁻¹ = 1.21 x 10⁻⁴ yrs⁻¹

t = Age = [ln(0.103/0.255) / - 1.21 x 10⁻⁴] yrs = 7500 years

5 0
3 years ago
The p-value of a statistical test depends on all of the following, except:
vaieri [72.5K]

Answer:

The correct option is e.

Explanation:

p-value is the probability value for a given statistical model, the probability that, when the null hypothesis is true.

For two two samples the formula of test statistics is

t=\frac{(\overline{x}_1-\overline{x}_2)-(\mu_1-\mu_2)}{\sqrt{\frac{s_1^2}{n_1}+\frac{s_2^2}{n_2}}}

where,

\overline{x} is sample mean

\mu is population mean.

s is standard deviation.

n is sample size.

Variance is the square of standard deviation.

It means variance, mean, numbers of samples is used in calculation of p-value.

Degree of freedom define the shape of the t-distribution that your t-test uses to calculate the p-value.

d.f.=n_1+n_2-2

p-value of a statistical test depends on all of the following, except median.

Therefore the correct option is e.

4 0
2 years ago
The weight of a sack potato in india is 50kgf. will the weight increase or decrease in bhutan. why​
AfilCa [17]

Answer:

Assume that the sack was initially close to the sea level. Its weight will increase even though its mass stays the same.

Explanation:

The weight of an object typically refers to the size of the planet's gravitational attraction (a force) on this object. That's not the same as the mass of the object. The weight of an object at a position depends on the size of the gravitational field there; on the other hand, the mass of the object is supposed to be same regardless of the location- as long as the object stays intact.

Let g denote the strength of the gravitational field at a certain point. If the mass of an object is m, its weight at that point will be m \cdot g.

Indeed, g \approx 9.81\; \rm N \cdot kg^{-1} on many places of the earth. However, this value is accurate only near the sea level. The equation for universal gravitation is a more general way for finding the strength of the gravitational field at an arbitrary height. Let G denote the constant of universal gravitation, and let M denote the mass of the earth. At a distance r from the center of the earth (where

\displaystyle g \approx \frac{G \cdot M}{r^2}.

The elevation of many places in Bhutan are significantly higher than that of many places in India. Therefore, a sack of potato in Bhutan will likely be further away from the center of the earth (larger r) compared to a sack of potato in India.

Note, that in the approximation, the value of g is (approximately, because the earth isn't perfectly spherical) inversely proportional to the distance from the center of the planet. The gravitational field strength

On the other hand, the weight of an object of fixed mass is proportional to the gravitational field strength. Therefore, the same bag of potatoes will have a smaller weight at most places in Bhutan compared to most places in India.

6 0
2 years ago
A chemist lectures about the following definition for acids and bases. The acid-base behavior is analyzed in terms of how electr
Y_Kistochka [10]

Answer:

the Lewis concept of acids and bases

Explanation:

8 0
3 years ago
Read 2 more answers
The weights of all elements are always compared to oxygen.
marishachu [46]

Answer:

The weights of all elements are always compared to the Carbon-12.

Explanation:

The weights of all elements are always compared to the Carbon-12 because the mass of carbon is 12 which is the exactly the sum of protons and neutrons.  

Oxygen was also considered the standard for some time but later this stander was rejected because in natural O¹⁷ and O¹⁸ were also present and this create the two different atomic mass tables.

AMU:

Atomic mass unit is define as the 1/12 the mass of an atom of carbon-12.

C12 has six neutron and six protons in the nucleus.

This unit is used to express the masses of atoms. We know that masses of atoms are very small and we do not have any such type of balance that can measure very small quantity. So that is way we use this scale to measure small quantity. For example, according to this scale

relative atomic mass of hydrogen is 1.008 amu

relative atomic mass of oxygen is 15.999 amu

relative atomic mass of uranium is 238.0289 amu

relative atomic mass of chlorine is 35.453 amu

7 0
2 years ago
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