QUES: There are three classes of components for oxide glasses: network formers, intermediates, and modifiers. The network formers (silicon, boron, germanium) form a highly cross-linked network of chemical bonds. The intermediates (titanium, aluminium, zirconium, beryllium, magnesium, zinc) can act as both network formers and modifiers, according to the glass composition. The modifiers (calcium, lead, lithium, sodium, potassium) alter the network structure; they are usually present as ions, compensated by nearby non-bridging oxygen atoms, bound by one covalent bond to the glass network and holding one negative charge to compensate for the positive ion nearby. Some elements can play multiple roles; e.g. lead can act both as a network former (Pb4+ replacing Si4+), or as a modifier.

What compensates for the bonds nearby?
What is the answer?
ANS: unanswerable
QUES: In response, Apple introduced a range of relatively inexpensive Macs in October 1990. The Macintosh Classic, essentially a less expensive version of the Macintosh SE, was the least expensive Mac offered until early 2001. The 68020-powered Macintosh LC, in its distinctive "pizza box" case, offered color graphics and was accompanied by a new, low-cost 512×384 pixel monitor. The Macintosh IIsi was essentially a 20 MHz IIci with only one expansion slot. All three machines sold well, although Apple's profit margin on them was considerably lower than that on earlier models.

How many expansion slots did the Macintosh IIsi have?
What is the answer?
ANS: only one
QUES: Yale has numerous athletic facilities, including the Yale Bowl (the nation's first natural "bowl" stadium, and prototype for such stadiums as the Los Angeles Memorial Coliseum and the Rose Bowl), located at The Walter Camp Field athletic complex, and the Payne Whitney Gymnasium, the second-largest indoor athletic complex in the world. October 21, 2000, marked the dedication of Yale's fourth new boathouse in 157 years of collegiate rowing. The Richard Gilder Boathouse is named to honor former Olympic rower Virginia Gilder '79 and her father Richard Gilder '54, who gave $4 million towards the $7.5 million project. Yale also maintains the Gales Ferry site where the heavyweight men's team trains for the Yale-Harvard Boat Race.

How much did the Richard Gilder Boathouse cost to construct?
What is the answer?
ANS:
$7.5 million