Sodium-Potassium Pump

An ACTIVE TRANSPORT mechanism of cell membranes to regulate pressure between the inside and outside of the cell and to pump potassium ions into the cell and keep sodium out, thereby preventing water retention and swelling within the cell. The sodium-potassium pump also maintains
the electrical charge within each cell. ATP is used as the energy source for the pump.

Soddy, Frederick (1877–1956)

Soddy, Frederick (1877–1956) British Physicist

Frederick Soddy was born at Eastbourne, Sussex, England,

on September 2, 1877, to Benjamin Soddy, a

London merchant. He was educated at Eastbourne College

and the University College of Wales, Aberystwyth.

After receiving a scholarship at Merton College,

Oxford, in 1895, he graduated three years later with

first-class honors in chemistry. After spending two

years doing research at Oxford, he moved to Canada,

and during 1900–02 he was demonstrator in the chemistry

department of McGill University, Montreal, working

with ERNEST RUTHERFORD on the problems of

radioactivity. He married Winifred Beilby in 1908.

From 1904 to 1914 he was a lecturer in physical chemistry

and radioactivity at the University of Glasgow,

and after teaching in Scotland, he was appointed professor

of chemistry at Oxford (1919–36).

He was one of the first to conclude in 1912 that

some elements can exist in forms that “are chemically

identical, and save only as regards the relatively few

physical properties which depend on atomic mass

directly, physically identical also.” He called them isotopes.

Later he promoted their use in determining geologic

age. He is credited (with others) with the

discovery of the element protactinium in 1917.

In 1921 he was awarded the Nobel Prize in chemistry

“for his contributions to our knowledge of the

chemistry of radioactive substances, and his investigations

into the origin and nature of isotopes.”

He published several books, including: Radioactivity

(1904), The Interpretation of Radium (1909), The

Chemistry of the Radioactive Elements (1912–14), Matter

and Energy (1912), Science and Life (1920), The

Interpretation of the Atom (1932), The Story of Atomic

Energy (1949), and Atomic Transmutation (1953).

Soddy died on September 22, 1956, at Brighton,

Sussex.

Some MCQ Question for your knowledge

1. How many milligrams are in 0.2 decigrams?
	(a)	20 milligrams
	(b)	2000 milligrams
	(c)	0.002 milligram
	(d)	0.00002 milligram
2. What would be the volume in liters of 640 g of oil if the density of the oil is 0.8 g/mL?
	(a)	800 liters
	(b)	0.8 liter
	(c)	512 liters
	(d)	0.5 liters
3. Five 1 peseta coins from Spain were dropped into a graduated cylinder containing 20.20 mL of water. The volume of the water increased to 22.05 mL. A single coin had a mass of 0.99 gram. What is the identity of the metal used for the Spanish 1 peseta coins?
		density of aluminum = 2.7 g/mL
		density of zinc = 7.1 g/mL
		density of copper = 9.0 g/mL
		density of silver = 10.0 g/mL
	(a)	aluminum
	(b)	zinc
	(c)	copper
	(d)	silver
4. The mass of a metal cylinder was determined on an analytical balance to be 50.208 g. The volume of the cylinder was measured and determined to be 5.6 mL. The density of the metal cylinder, expressed to the proper number of significant figures, is...
	(a)	8.9657 g/mL
	(b)	9.0 g/mL
	(c)	0.11153 g/mL
	(d)	0.11 g/mL

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