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3 years ago

The pen on seismograph swings freely.

Chemistry

1 answer:

Sever21 [200]3 years ago

7 0

This statment is false, the pen on a seismograph does not swing freely.

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What are the groups on the periodic table let us predict how elements will react

cluponka [151]

Answer:

The vertical columns are called groups.

Explanation:

Periodic table consist of vertical columns and horizontal rows.

Vertical columns are called groups while horizontal rows are called periods.

There are seven periods and 18 groups in periodic table.

The elements in same group have similar properties and can react in a similar way.

The elements in same group have same number of valance electrons that's why their reactivity is same.

Consider the example of alkaline earth metals. They are present in group two and have same number of valance electrons (two valance electrons).

They react with oxygen and form oxide.

2Ba + O₂ → 2BaO

2Mg + O₂ → 2MgO

2Ca + O₂ → 2CaO

this oxide form hydroxide when react with water,

BaO + H₂O → Ba(OH)₂

MgO + H₂O → Mg(OH)₂

CaO + H₂O → Ca(OH)₂

With sulfur,

Mg + S → MgS

Ca + S → CaS

Ba + S → BaS

7 0

3 years ago

17. Physical properties of a material include all but ________________.

Amiraneli [1.4K]

Answer:

17)c: the reactivity of a metal.

Explanation:

8 0

3 years ago

Hi GUYS PLEASE HELP ME YOU KNOW I HELP YOU WHEN YOU NEED IT MOST SO HERE IT GOES WHICH SEQUENCE REPRESENTS THE ORDER OF DEVELOPM

exis [7]

To answer your question, the answer is number 1. hope this help

6 0

3 years ago

A 5.00-mL sample of blood was treated with trichloroacetic acid to precipitate proteins. After centrifugation, the resulting sol

Anarel [89]

Explanation:

According to the Beer-lambert' s law,

Absrobance = absrobptitvity × lenght × concentration

So, if we will plot a graph between absrobance and concentration then we will obtain a straight line

Hence, formula to calculate slope of the graph is as follows.

The slope of graph = $\frac{\text{difference in absrobance at two points}}{\text{difference in concentrations at those points}}$

The given data is as follows.

$A_{1}$ = 0.412 (first point)

$A_{2}$ = 0.642 (second point)

$C_{1}$ = 0.240 ppm (first point)

$C_{2}$ = 0.475 ppm (second point)

Hence, putting these values into the above formula we will calculate the value of slope as follows.

Slope = $\frac{\text{difference in absrobance at two points}}{\text{difference in concentrations at those points}}$

= $\frac{0.642 - 0.412}{0.475 - 0.240}$

= $\frac{0.23}{0.235}$

= 0.978

It is known that for the graph, line equation can be written as follows.

y = mx + c ........... (1)

where, C = intercept

m = slope

Hence, calculate the value of intercept as follows.

0.412 = $0.24 \times 0.978$ + c

c = 0.178

As it is given that the absorbance values 0.454 (the y-axis value). Therefore, putting this value into equation (1) we get the following.

y = mx + c

0.454 = $x \times 0.978$ + 0.178

0.276 = 0.978x

x = 0.282 ppm

Thus, we can conclude that the concentration of Pb in the given sample is 0.282 ppm.

3 0

3 years ago

NO LINKS please help!

GarryVolchara [31]

Answer:

True True False

Explanation:

4 0

3 years ago