QUES: Established acts benefited from the new commercial climate, with Whitesnake's self-titled album (1987) selling over 17 million copies, outperforming anything in Coverdale's or Deep Purple's catalogue before or since. It featured the rock anthem "Here I Go Again '87" as one of 4 UK top 20 singles. The follow-up Slip of the Tongue (1989) went platinum, but according to critics Steve Erlwine and Greg Prato, "it was a considerable disappointment after the across-the-board success of Whitesnake". Aerosmith's comeback album Permanent Vacation (1987) would begin a decade long revival of their popularity. Crazy Nights (1987) by Kiss was the band's highest charting release in the US since 1979 and the highest of their career in the UK. Motley Crue with Girls, Girls, Girls (1987) continued their commercial success and Def Leppard with Hysteria (1987) hit their commercial peak, the latter producing seven hit singles (a record for a hard rock act). Guns N' Roses released the best-selling debut of all time, Appetite for Destruction (1987). With a "grittier" and "rawer" sound than most glam metal, it produced three top 10 hits, including the number one "Sweet Child O' Mine". Some of the glam rock bands that formed in the mid-1980s, such as White Lion and Cinderella experienced their biggest success during this period with their respective albums Pride (1987) and Long Cold Winter (1988) both going multi-platinum and launching a series of hit singles. In the last years of the decade, the most notable successes were New Jersey (1988) by Bon Jovi, OU812 (1988) by Van Halen, Open Up and Say... Ahh! (1988) by Poison, Pump (1989) by Aerosmith, and Motley Crue's most commercially successful album Dr. Feelgood (1989). New Jersey spawned five Top 10 singles, a record for a hard rock act. In 1988 from 25 June to 5 November, the number one spot on the Billboard 200 album chart was held by a hard rock album for 18 out of 20 consecutive weeks; the albums were OU812, Hysteria, Appetite for Destruction, and New Jersey. A final wave of glam rock bands arrived in the late 1980s, and experienced success with multi-platinum albums and hit singles from 1989 until the early 1990s, among them Extreme, Warrant Slaughter and FireHouse. Skid Row also released their eponymous debut (1989), reaching number six on the Billboard 200, but they were to be one of the last major bands that emerged in the glam rock era.

Def Leppard's album Hysteria churned out how many hit singles?
What is the answer?
ANS: seven
QUES: In a conventional lamp, the evaporated tungsten eventually condenses on the inner surface of the glass envelope, darkening it. For bulbs that contain a vacuum, the darkening is uniform across the entire surface of the envelope. When a filling of inert gas is used, the evaporated tungsten is carried in the thermal convection currents of the gas, depositing preferentially on the uppermost part of the envelope and blackening just that portion of the envelope. An incandescent lamp that gives 93% or less of its initial light output at 75% of its rated life is regarded as unsatisfactory, when tested according to IEC Publication 60064. Light loss is due to filament evaporation and bulb blackening. Study of the problem of bulb blackening led to the discovery of the Edison effect, thermionic emission and invention of the vacuum tube.

What are the primary causes of light loss?
What is the answer?
ANS: Light loss is due to filament evaporation and bulb blackening
QUES: By summer 1918, a million American soldiers, or "doughboys" as they were often called, of the American Expeditionary Forces were in Europe under the command of John J. Pershing, with 25,000 more arriving every week. The failure of Germany's spring offensive exhausted its reserves and they were unable to launch new offensives. The German Navy and home front then revolted and a new German government signed a conditional surrender, the Armistice, ending the war against the western front on November 11, 1918.

Who had overall command of the American forces in Europe?
What is the answer?
ANS:
John J. Pershing