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#1 Re: Ganesh's Puzzles » 10 second questions » Today 18:39:56


The solution #6295 is correct. Splendid, Monox D. I-Fly!

#6296. Find the value of


#2 Re: Ganesh's Puzzles » 10 second questions » Today 14:56:42


The solution #6294 is correct. Neat work, Monox D. I-Fly!

#6295. Seven times a two-digit number is equal to four times the number obtained by reversing the digits. If the difference between the digits is 3, find the number.

#3 Re: Guestbook » Correct Answer to 12 Days of Christmas Puzzle » Yesterday 22:50:06


It's from the MIF puzzles:

Thank you, bob bundy!

#4 Re: Ganesh's Puzzles » 10 second questions » Yesterday 22:40:07


The solution #6293 is correct. Excellent, Monox D. I-Fly!

#6294. If we add 1 to the numerator and subtract 1 from the denominator, a fraction becomes 1. It also becomes 1/2 if we only add 1 to the denominator. What is the fraction?

#5 Re: Ganesh's Puzzles » Oral puzzles » Yesterday 15:20:30


The solution #3853 is correct. Keep it up, Monox D. I-Fly!

#3854. Find the value of k if

has equal roots.

#6 Re: Ganesh's Puzzles » 10 second questions » Yesterday 15:14:20


The solution #6292 is correct. Brilliant, Monox D. I-Fly!

#6293. A fraction becomes 1/3 if 1 is subtracted from both its numerator and denominator. If 1 is added to both the numerator and denominator, it becomes 1/2. Find the fraction.

#7 Re: Guestbook » Correct Answer to 12 Days of Christmas Puzzle » Yesterday 15:03:59

Hi Roger L,

You have not given the text of the puzzle. Please provide the entire problem.

#8 Re: Ganesh's Puzzles » 10 second questions » Yesterday 14:53:53


#6292. If the Greatest Common Divisor of two numbers 26 and 169 is 13, find the Least Common Multiple of the two numbers.

#9 Re: Ganesh's Puzzles » Oral puzzles » Yesterday 14:39:22


The solution #3852 is correct. Good going, Monox D. I-Fly!

#3853. If the sum and the product of the roots of the equation

are equal, then find the value of k.

#10 Re: This is Cool » Miscellany » Yesterday 00:57:17

40) pH Value

pH, quantitative measure of the acidity or basicity of aqueous or other liquid solutions. The term, widely used in chemistry, biology, and agronomy, translates the values of the concentration of the hydrogen ion—which ordinarily ranges between about 1 and

gram-equivalents per litre—into numbers between 0 and 14. In pure water, which is neutral (neither acidic nor alkaline), the concentration of the hydrogen ion is
gram-equivalents per litre, which corresponds to a pH of 7. A solution with a pH less than 7 is considered acidic; a solution with a pH greater than 7 is considered basic, or alkaline.

The measurement was originally used by the Danish biochemist S.P.L. Sørensen to represent the hydrogen ion concentration, expressed in equivalents per litre, of an aqueous solution: pH = −log[H+] (in expressions of this kind, enclosure of a chemical symbol within square brackets denotes that the concentration of the symbolized species is the quantity being considered).

Because of uncertainty about the physical significance of the hydrogen ion concentration, the definition of the pH is an operational one; i.e., it is based on a method of measurement. The U.S. National Bureau of Standards has defined pH values in terms of the electromotive force existing between certain standard electrodes in specified solutions.

The pH is usually measured with a pH meter, which translates into pH readings the difference in electromotive force (electrical potential or voltage) between suitable electrodes placed in the solution to be tested. Fundamentally, a pH meter consists of a voltmeter attached to a pH-responsive electrode and a reference (unvarying) electrode. The pH-responsive electrode is usually glass, and the reference is usually a mercury-mercurous chloride (calomel) electrode, although a silver-silver chloride electrode is sometimes used. When the two electrodes are immersed in a solution, they act as a battery. The glass electrode develops an electric potential (charge) that is directly related to the hydrogen-ion activity in the solution, and the voltmeter measures the potential difference between the glass and reference electrodes. The meter may have either a digital or an analog (scale and deflected needle) readout. Digital readouts have the advantage of exactness, while analog readouts give better indications of rates of change. Battery-powered portable pH meters are widely used for field tests of the pH of soils. Tests of pH may also be performed, less accurately, with litmus paper or by mixing indicator dyes in liquid suspensions and matching the resulting colours against a colour chart calibrated in pH.

In agriculture, the pH is probably the most important single property of the moisture associated with a soil, since that indication reveals what crops will grow readily in the soil and what adjustments must be made to adapt it for growing any other crops. Acidic soils are often considered infertile, and so they are for most conventional agricultural crops, although conifers and many members of the family Ericaceae, such as blueberries, will not thrive in alkaline soil. Acidic soil can be “sweetened,” or neutralized, by treating it with lime. As soil acidity increases so does the solubility of aluminum and manganese in the soil, and many plants (including agricultural crops) will tolerate only slight quantities of those metals. Acid content of soil is heightened by the decomposition of organic material by microbial action, by fertilizer salts that hydrolyze or nitrify, by oxidation of sulfur compounds when salt marshes are drained for use as farmland, and by other causes.


#11 Re: Ganesh's Puzzles » Oral puzzles » 2017-12-10 21:34:26


The solution #3851 is correct. Excellent, Monox D. I-Fly!

#3852. If one root of the equation

is 1, then find its other root.

#12 Re: Ganesh's Puzzles » Oral puzzles » 2017-12-10 18:43:40


The solution #3850 (two values) is correct. Keep it up, Monox D. I-Fly!

#3851. If one root of the equation

is 2, then find the other root.

#13 Re: Ganesh's Puzzles » 10 second questions » 2017-12-10 18:20:46


The solution #6290 is correct. Neat work, Monox D. I-Fly!

#6291. Express this number as a rational number:


#14 Re: Ganesh's Puzzles » 10 second questions » 2017-12-10 15:54:54


#6290. Find the Greatest Common Divisor of 95 and 152.

#15 Re: Ganesh's Puzzles » Oral puzzles » 2017-12-10 15:34:55


The solution #3849 (three values) is correct. Excellent, Monox D. I-Fly!

#3850. Find the values of k for which the quadratic equation

has real and equal roots.

#16 Re: Dark Discussions at Cafe Infinity » crème de la crème » 2017-12-10 00:19:34

245) Benjamin Spock

Benjamin Spock, in full Benjamin McLane Spock, byname Dr. Spock (born May 2, 1903, New Haven, Connecticut, U.S.—died March 15, 1998, La Jolla, California), American pediatrician whose books on child-rearing, especially his Common Sense Book of Baby and Child Care (1946; 6th ed., 1992), influenced generations of parents and made his name a household word.

Spock received his medical degree in 1929 from Columbia University’s College of Physicians and Surgeons and trained for six years at the New York Psychoanalytic Institute. He practiced pediatrics in New York City while teaching the subject at the Cornell University Medical College from 1933 to 1947. Spock wrote Baby and Child Care partly to counteract the rigid pediatric doctrines of his day, which emphasized strict feeding schedules for infants and discouraged open displays of affection between parent and child. Spock, by contrast, encouraged understanding and flexibility on the part of parents, and he stressed the importance of listening to children and appreciating their individual differences. From its first appearance in 1946, Baby and Child Care served as the definitive child-rearing manual for millions of American parents in the “baby boom” that followed World War II. Spock’s approach was criticized as overly permissive by a minority of physicians, and he was even blamed for having helped form the generation of young Americans that protested the Vietnam War and launched the youth counterculture movement of the 1960s.

Spock taught child development at Western Reserve University (now Case Western Reserve University) in Cleveland, Ohio, from 1955 to 1967, when he resigned in order to devote himself more fully to the antiwar movement. Spock’s bitter opposition to U.S. involvement in the Vietnam War during the 1960s led to his trial and conviction (1968) for counseling draft evasion—a conviction overturned on appeal. In 1972 he was the presidential candidate of the pacifist People’s Party.

Spock’s many other books on child care include Dr. Spock Talks with Mothers (1961), Raising Children in a Difficult Time (1974), and Dr. Spock on Parenting (1988). He also wrote Decent and Indecent: Our Personal and Political Behavior (1970). In 1989 Spock on Spock: A Memoir of Growing Up with the Century, edited by Spock’s second wife, Mary Morgan, was published. By the time Spock died in 1998, his Baby and Child Care had sold nearly 50 million copies worldwide and been translated into 39 languages.


#17 Re: This is Cool » Miscellany » 2017-12-09 01:30:03

39) Nickel

Nickel is a strong, lustrous, silvery-white metal that is a staple of our daily lives and can be found in everything from the batteries that power our television remotes to the stainless steel that is used to make our kitchen sinks.


Atomic Symbol: Ni
Atomic Number: 28
Element Category: Transition metal
Density: 8.908 g/cubic centimeters
Melting Point: 2651 °F (1455 °C)
Boiling Point: 5275 °F (2913 °C)
Moh’s Hardness: 4.0


Pure nickel reacts with oxygen and, therefore, is seldom found on the earth's surface, despite being the fifth most abundant element on (and in) our planet. In combination with iron, nickel is extremely stable, which explains both its occurrence in iron-containing ores and its effective use in combination with iron to make stainless steel.

Nickel is very strong and resistant to corrosion, making it excellent for strengthening metal alloys. It is also very ductile and malleable, properties that allow its many alloys to be shaped into wire, rods, tubes, and sheets.


Pure nickel was first extracted by Baron Axel Fredrik Cronstedt in 1751, but it was known to exist much earlier. Chinese documents from around 1500BC make reference to 'white copper' (baitong), which was very likely an alloy of nickel and silver. Fifteenth century German miners, who believed they could extract copper from nickel ores in Saxony, referred to the metal as kupfernickel - 'the devil's copper' - partly due to their futile attempts to extract copper from the ore, but also likely in part due to the health effects caused by the high math content in the ore.

In 1889, James Riley made a presentation to the Iron and Steel Institute of Great Britain on how the introduction of nickel could strengthen traditional steels. Riley's presentation resulted in a growing awareness of nickel's beneficial alloying properties and coincided with the discovery of large nickel deposits in New Caledonia and Canada.

By the early 20th century, the discovery of ore deposits in Russia and South Africa made large-scale production of nickel possible. Not long after, World War I and World War II resulted in a significant increase in steel and, consequently, nickel demand.


Nickel is primarily extracted from the nickel sulphides pentlandite, pyrrhotite, and millerite, which contain about 1% nickel content, and the iron-containing lateritic ores limonite and garnierite, which contain about 4% nickel content. Nickel ores are mined in 23 countries, while nickel is smelted in 25 different countries.

The separation process for nickel is highly dependent upon the type of ore. Nickel sulphides, such as those found in the Canadian Shield and Siberia, are generally found deep underground, making them labor intensive and expensive to extract. However, the separation process for these ores is much cheaper than for the lateritic variety, such as those found in New Caledonia. Moreover, nickel sulphides often have the benefit of containing impurities of other valuable elements that can be economically separated.

Sulphide ores can be separated using froth flotation and hydrometallurgical or magnetic processes to create nickel matte and nickel oxide.

These intermediate products, which usually contain 40-70% nickel, are then further processed, often using the Sherritt-Gordon Process.

The Mond (or Carbonyl) Process is the most common and efficient method to treat nickel sulphide. In this process, the sulphide is treated with hydrogen and fed into a volatilization kiln. Here it meets carbon monoxide at about 140F° (60C°) to form nickel carbonyl gas. The nickel carbonyl gas decomposes on the surface of pre-heated nickel pellets that flow through a heat chamber until they reach the desired size. At higher temperatures, this process can be used to form nickel powder.

Lateritic ores, by contrast, are usually smelted by pyro-metallic methods because of their high iron content. Lateritic ores also have a high moisture content (35-40%) that requires drying in a rotary kiln furnace.

It produces nickel oxide, which is then reduced using electric furnaces at temperatures between 2480-2930 F° (1360-1610 C°) and volatilized to produce Class I nickel metal and nickel sulfate.

Due to the naturally occurring iron content in lateritic ores, the end product of most smelters working with such ores is ferro-nickel, which can be used by steel producers after silicon, carbon, and phosphorus impurities are removed.

By country, the largest producers of nickel in 2010 were Russia, Canada, Australia and Indonesia. The largest producers of refined nickel are Norilsk Nickel, Vale S.A., and Jinchuan Group Ltd. At present, only a small percentage of nickel is produced from recycled materials.


Nickel is one of the most widely used metals on the planet. According to the Nickel Institute, the metal is used in over 300,000 different products. Most often it is found in steels and metal alloys, but it is also used in the production of batteries and permanent magnets.

Stainless Steel:

About 65% of all nickel produced goes into stainless steel.

Austenitic steels are non-magnetic stainless steels that contain high levels of chromium and nickel, and low levels of carbon.  This group of steels - classified as 300 series stainless - are valued for their formability and resistance to corrosion. Austenitics are the most widely used   grade of stainless steel.

The nickel-containing austenitic range of stainless steels is defined by their face-centered cubic (FCC) crystal structure, which has one atom at each corner of the cube and one in the middle of each face. This grain structure forms when a sufficient quantity of nickel is added to the alloy (eight to ten percent in a standard 304 stainless steel alloy).


#18 Re: Ganesh's Puzzles » 10 second questions » 2017-12-09 00:37:09


#6289. Find the largest number which divides 615 and 963 leaving reminder of 6 in each case.

#19 Re: Ganesh's Puzzles » Oral puzzles » 2017-12-09 00:22:14


#3849. The hypotenuse of a grassy land in the shape of a right triangle is 1 meter more than twice the shortest side. If the third side is 7 meters more than the shortest side, find the sides of the grassy land.

#20 Re: Dark Discussions at Cafe Infinity » crème de la crème » 2017-12-08 00:42:03

244) John Harrison

John Harrison, (born March 1693, Foulby, Yorkshire, Eng.—died March 24, 1776, London), English horologist who invented the first practical marine chronometer, which enabled navigators to compute accurately their longitude at sea.

Harrison, the son of a carpenter and a mechanic himself, became interested in constructing an accurate chronometer in 1728. Several unfortunate disasters at sea, caused ostensibly by poor navigation, prompted the British government to create a Board of Longitude empowered to award £20,000 to the first man who developed a chronometer with which longitude could be calculated within half a degree at the end of a voyage to the West Indies. Harrison completed his first chronometer in 1735 and submitted it for the prize. He then built three more instruments, each smaller and more accurate than its predecessor. In 1762 Harrison’s famous No. 4 marine chronometer was found to be in error by only five seconds (1 1/4′ longitude) after a voyage to Jamaica. Although his chronometers all met the standards set up by the Board of Longitude, he was not awarded any money until 1763, when he received £5,000, and not until 1773 was he paid in full. The only feature of his chronometers retained by later manufacturers was a device that keeps the clock running while it is being wound.


#21 Re: Ganesh's Puzzles » Oral puzzles » 2017-12-07 18:39:56


The solution #3847 (two parts) is correct. Excellent, Monox D. I-Fly!

#3848. An airplane takes 1 hour less for a journey of 1200 kilometers if its speed is increased by 100 kilometers per hour from its usual speed. Find its usual speed.

#22 Re: Ganesh's Puzzles » Oral puzzles » 2017-12-07 15:32:11


The solution #3846 is correct. Excellent, Monox D. I-Fly!

#3847. A fast train take one hour less than a slow train for a journey of 200 kilometers. If the speed of the slow train is 10 kilometers per hour than that of the fast train, find the speed of the two trains.

#23 Re: Ganesh's Puzzles » 10 second questions » 2017-12-07 15:24:32


Good attempt, Monox D. I-Fly!

#6288. Find the least number that is divisible by all the numbers between 1 and 10, both inclusive.

#24 Re: Ganesh's Puzzles » 10 second questions » 2017-12-07 14:08:47


The solution #6286 (two parts) is correct. Neat work, Monox D. I-Fly!

#6287. The Least Common Multiple (LCM) and Greatest Common Divisor (GCD) of two numbers are 180 and 6 respectively. If one of the numbers is 30, find the other number.

#25 Re: Ganesh's Puzzles » Oral puzzles » 2017-12-07 13:57:06


The solution #3845 is correct. Good work, Monox D. I-Fly!

#3846. A passenger train takes 3 hours less for a journey of 360 kilometers, if its speed is increased by 10 kilometers per hour from its usual speed. What is the usual speed?

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