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3 years ago

14

When bacteria have multiplied at least 1000 times, what is the pattern of growth that can be seen with the naked eye is called?

1 answer:

MAXImum [283]3 years ago

6 0

Answer:

Colony

Explanation:

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if matter is made of many tiny particles, why does it seem to be continuous? Why doesn’t water seem to behave like sand?

valkas [14]

Answer:

Explanation:

if matter is made of many tiny particles, why does it seem to be continuous? Why doesn’t water seem to behave like sand?

Water and some other molecules exhibit a property know as hydrogen bonding. A hydrogen atom in one molecule of water is attracted to the oxygen in a neighboring molecules of water.'

The force of this attraction is less than a standard chemical attractive force, but it is real and measurable.

When billions and trillions of water molecules are held together by this force, the small amount of molecule to molecule force is added up to a tremendous force. That is why even though sulfur is below oxygen on the periodic table, hydrogen sulfide is a gas while hydrogen oxide is a liquid at room temperature.

Hydrogen bonding explains the unique properties of ice, liquid water and steam,We all know water exists in several forms such as solid, liquid and ice. Water boils at 100  C and freezes at 32  F, right? Am I correct? Let us look at some of the chemistry behind forms of water.

The strong polar bond between water molecules creates water cohesion.

As they are cooled, aggregates of most other substances increase monotonically in density becoming progressively heavier -- the colder they are, the more tightly packed their molecules become. But water possesses a peculiar physical feature: ice expands, so it is lighter than liquid water (i. e., ice floats). When water trapped in rock crevices freezes, it breaks rocks (and pipes).

Water is vital to all known life forms, that is, all those on planet Earth. It is so integral to life as we know it that many biologists cannot even envision life without water (although that might be possible). Indeed, the physical properties of water dictate critical thermal limits for living systems.

In one sci-fi story, an alien refers to humans as "ugly bags of mostly water" -- our bodies are about 60-70% water, depending upon how dehydrated we are at any given time. Humans use massive amounts of freshwater to drink, cook, bathe, flush toilets, do laundry, fill swimming pools, irrigate yards and gardens, run flowing fountains, and for recreation. Precious clean water is often wasted, such as when people leave tap water running while washing their hands or brushing their teeth. The personal water consumption of an average American is about 200 gallons per day, but when industrial and energy usage is added in, per capita freshwater usage is more than 2000 gallons/day. People in third world countries use much less water, of course.

Most freshwater is claimed or "owned" and there is not enough to go around. Approximately half of the world's population of people do not even have adequate access to clean drinking water. One of the major symptoms of the human overpopulation crisis is shortages of available fresh water. Wars will be fought over water.

7 0

2 years ago

determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth m

mamaluj [8]

This is an incomplete question, here is a complete question.

Determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices.

(a) $1s^22s^22p^63s^23p^5$

(b) $1s^22s^22p^63s^23p^63d^74s^2$

(c) $1s^22s^22p^63s^23p^63d^{10}4s^24p^6$

(d) $1s^22s^22p^63s^23p^63d^4s^1$

Answer :

(a) $1s^22s^22p^63s^23p^5$ → Halogen

(b) $1s^22s^22p^63s^23p^63d^74s^2$ → Transition metal

(c) $1s^22s^22p^63s^23p^63d^{10}4s^24p^6$ → Transition metal

(d) $1s^22s^22p^63s^23p^63d^4s^1$ → Transition metal

Explanation :

Inert gas : These are the gases which lie in group 18.

Their general electronic configuration is: $ns^2np^6$ where n is the outermost shell.

Halogen : These are the elements which lie in group 17.

Their general electronic configuration is: $ns^2np^5$ where n is the outermost shell.

An alkali metal : These are the elements which lie in group 1.

Their general electronic configuration is: $ns^1$ where n is the outermost shell.

An alkaline earth metal : These are the elements which lie in group 2.

Their general electronic configuration is: $ns^2$ where n is the outermost shell.

Transition elements : They are the elements which lie between 's' and 'p' block elements. These are the elements which lie in group 3 to 12. The valence electrons of these elements enter d-orbital.

Their general electronic configuration is: $(n-1)d^{1-10}ns^{0-2}$ where n is the outermost shell.

(a) $1s^22s^22p^63s^23p^5$

The element having this electronic configuration belongs to the halogen family.

(b) $1s^22s^22p^63s^23p^63d^74s^2$

The element having this electronic configuration belongs to the transition family.

(c) $1s^22s^22p^63s^23p^63d^{10}4s^24p^6$

The element having this electronic configuration belongs to the transition family.

(d) $1s^22s^22p^63s^23p^63d^4s^1$

The element having this electronic configuration belongs to the transition family.

4 0

2 years ago

A 500.0 mL sample of 0.18 MHClO4 is titrated with 0.27 MCsOH. Determine the pH of the solution after the addition of 250.0 mL of

NNADVOKAT [17]

Answer:

or i go

Explanation:

i must go ooon sjsj

7 0

2 years ago

The half life of a certain radioactive element is 800 years. How old is an object if only 12.5% of radioactive atoms in it remai

Levart [38]

Given, half life of a certain radioactive element = 800 years.

Amount of substance remaining at time t = 12.5%

Lets consider the initial amount of the radioactive substance = 100%

Using the half life equation:

A = A₀(1/2)^t/t₁/₂

where A₀ is the amount of radioactive substance at time zero and A is the amount of radioactive substance at time t, and t₁/₂ is the half-life of the radioactive substance.

Plugging the given data into the half life equation we have,

12.5 = 100 . (1/2)^t/800

12.5/100 = (1/2)^t/800

0.125 = (0.5)^t/800

(0.5)^3 = (0.5)^t/800

3 = t/800

t = 2400 years

Thus the object is 2400 years old.

6 0

3 years ago

Balance each of the following redox reactions occurring in basic solution.MnO−4(aq)+Br−(aq)→MnO2(s)+BrO−3(aq)Express your answer

Ahat [919]

Answer : The balanced chemical equation is,

$2MnO_4^-(aq)+Br^-(aq)+H_2O(l)\rightarrow 2MnO_2(s)+BrO_3^-(aq)+2OH^-(aq)$

Explanation :

Rules for the balanced chemical equation in basic solution are :

First we have to write into the two half-reactions.
Now balance the main atoms in the reaction.
Now balance the hydrogen and oxygen atoms on both the sides of the reaction.
If the oxygen atoms are not balanced on both the sides then adding water molecules at that side where the more number of oxygen are present.
If the hydrogen atoms are not balanced on both the sides then adding hydroxide ion $(OH^-)$ at that side where the less number of hydrogen are present.
Now balance the charge.

The half reactions in the basic solution are :

Reduction : $MnO_4^-(aq)+2H_2O(l)+3e^-\rightarrow MnO_2(s)+4OH^-(aq)$ ......(1)

Oxidation : $Br^-(aq)+6OH^-(aq)\rightarrow BrO_3^-(aq)+3H_2O(l)+6e^-$ .......(2)

Now multiply the equation (1) by 2 and then added both equation, we get the balanced redox reaction.

The balanced chemical equation in a basic solution will be,

$2MnO_4^-(aq)+Br^-(aq)+H_2O(l)\rightarrow 2MnO_2(s)+BrO_3^-(aq)+2OH^-(aq)$

8 0

2 years ago